Quiz Electronics Engineering 31 Oct 2020

Quiz Electronics Engineering
Exam: NIC
Topic: Miscellaneous
Date: 31/10/2020

Each Question carries 1 Mark
Negative Marking: 1/4
Time: 10 Minutes

Q1. Which amplifier will be preferred for highest gain?
(a) Darlington pair
(b) Cascade amplifier
(c) Cascode amplifier
(d) Depends on the circuitry

Q2. Identify the correct condition for a semiconductor to be electrically neutral.
(a) N_D – p = N_A + n
(b) N_D + p = N_A + n
(c) N_D + p = N_A – n
(d) N_D – p = N_A – n

Q3. Two rectangular waveform of duration T_1 and T_2 seconds are convolved. What is the shape of the resulting waveform?
(a) Triangular
(b) Rectangular
(c) Trapezoidal
(d) semi-circle

Q4. A phase-locked loop (PLL) is a feedback circuit consisting of a:
(a) Phase detector
(b) Low-pass filter
(c) VCO
(d) All of these

Q5. How many bits are used in data bus of 8085?
(a) 7
(b) 8
(c) 9
(d) 16

Q6. If a fair coin is tossed four times. What is the probability that two heads and two tails will result?
(a) 3/8
(b) 1/2
(c) 5/8
(d) 3/4

Q7. Match List-I with List-II and select the correct answer using codes given below the lists:
List-I List-II
A. MMF 1. Conductivity
B. Magnetic Flux 2. Electric Current
C. Reluctance 3. EMF
D. Permeability 4. Resistance
Codes:
A B C D
(a) 3 4 2 1
(b) 1 2 4 3
(c) 3 2 4 1
(d) 1 4 2 3

Q8. In a certain 2-input logic gate, when A = 0, B = 0 and output C = 1, it must be …
(a) OR gate
(b) XOR gate
(c) AND gate
(d) NAND gate

Q9. Three resistance of 5 Ω each are connected in star. Values of equivalent delta resistances are
(a) 15 Ω each
(b) 2.5 Ω each
(c) 5/3 Ω each
(d) 1.5 Ω each

Q10. In OSI network architecture, the dialogue control and token management are responsibility of:
(a) data link layer
(b) Session layer
(c) transport layer
(d) network layer

SOLUTIONS

S1. Ans.(c)
Sol. A Cascode Amplifier consists of a Common Emitter stage loaded by the emitter of a Common Base stage. It has larger bandwidth because Miller effect is negligible. Its advantages are: –
larger bandwidth
high gain
moderately high input impedance
high output impedance

S2. Ans (b)
Sol. According to Law of Electrical Neutrality:
⇒ N_D + p = N_A + n
where,
N_A is acceptor concentration
N_D is donor concentration

S3. Ans.(a)
Sol. If two rectangular waveform have different duration then after convolution the shape of resulting waveform is Trapezoidal but if two rectangular waveform have same duration then after convolution the shape of resulting waveform is triangular.

S4. Ans.(d)
Sol. When PLL is used as FM demodulator, multiplier is replaced by phase detector.

S5. Ans.(b)

S6. Ans.(a)
Sol. Given:
p=P(H)=1/2
Applying the formula for binomial distribution, we get
P(X=2)= (_ ^4)C_2 (1/2)² (1-1/2)^(4-2)
⇒ P(X = 2) = (_ ^4)C_2 (1/2)^2 (1/2)² (_ ^4)C_2 /2^4
So, P(X = 2) = 6/16=3/8

S7. Ans.(c)

S8. Ans (d)
Sol. Truth Table of NAND gate: –

S9. Ans.(a)
Sol. If value of all three resistance in star circuit is same then during Star-Delta transformation the respective resistance increases by 3 times.

So, The equivalent delta resistance = 15Ω each.

S10. Ans.(b)
Sol. Session layer is responsible for setting up, controlling & then tearing down session between two computers. It helps in managing flow of data communication during a connection between two computers. The function of this layer are dialogue control, token management and synchronization.

Quiz Electronics Engineering 26 Oct 2020

Quiz Electronics Engineering
Exam: NIC
Topic: Miscellaneous
Date: 26/10/2020

Each Question carries 1 Mark
Negative Marking: 1/4
Time: 10 Minutes

Q1. To deliver a message to the correct application program running on a host, the _______ address must be consulted.
(a) IP
(b) Port
(c) MAC
(d) None of the above

Q2. An a.c series circuit has R = 6 Ω,X_L=20 Ω and X_C=12Ω. The circuit power factor will be
(a) 0.8 Leading
(b) 0.5 Lagging
(c) 0.6 Leading
(d) 0.6 Lagging

Q3. In 8085 to disable the whole interrupt(except TRAP):
(a) the interrupt instruction may be used
(b) the SI instruction may be used.
(c) the DI instruction may be used.
(d) the EI instruction may be used

Q4. The main factor that determines the accuracy of a reconstructed PCM signal is the
(a) number of bits used for quantization
(b) pulse repetition rate
(c) pulse amplitude
(d) Signal bandwidth

Q5. The number 1000_2 is equivalent to decimal number
(a) one thousand
(b) eight
(c) four
(d) sixteen

Q6. Which of the following device has characteristics closed to that of an ideal current source?
(a) Gas diode
(b) Crystal diode
(c) Transistor in CB mode
(d) All of the above

Q7. Which one of the following systems described by the following input-output relations is non-linear?
(a) y(n) = x^2(n)
(b) y(n) = x(n^2)
(c) y(n) = n^2x(n)
(d) y(n) = nx(2n)

Q8. Match List-I(Electromagnetic Law) with List-II(Differential Form) and select the correct answer using codes given below the lists:
List-I List-II
A. Ampere’s Law 1. ∇.D ⃗ = ρ_v
B. Faraday’s Law 2. ∇.J ⃗ = -(∂H ⃗)/∂t
C. Gauss Law 3. ∇ × H ⃗ = J ⃗ + (∂D ⃗)/∂t
D. Current Continuity equation 4. ∇ × E ⃗ = -(∂B ⃗)/∂t
Codes:
A B C D
(a) 1 2 3 4
(b) 3 4 1 2
(c) 1 4 3 2
(d) 3 2 1 4

Q9. Which of the following addressing mode is not usable in XCH instruction of 8085 microprocessor?
(a) Direct Addressing
(b) Indirect Addressing
(c) Immediate Addressing
(d) Register Addressing

Q10. Turn-off time of a thyristor is
(a) depends on load
(b) depends upon junction temperature
(c) depends upon forward current
(d) both (b) and (c)

SOLUTIONS

S1. Ans.(b)
Sol.
IP address tells about the location of the network.
MAC address is a unique address for every device.
Port address identifies a process or service which are to be carried to the device present at the destination.

S2. Ans(d)
Sol.
Z=√(6^2+(20-12)²) = 10
ϕ= R/Z = 6/10 = 0.6 lagging

S3. Ans.(c)
Sol. Destination Index(DI) instruction will disable all the instructions except TRAP.

S4. Ans.(a)
Sol. In PCM signal, quantization noise depends only on the number of bits used for quantization.
Qe = Δ/2 = (Dynamic Range)/(2.2^n )
Therefore, The main factor that determines the accuracy of a reconstructed PCM signal is number of bits used for quantization.

S5. Ans.(b)
Sol. Here,
⇒ 10002 = 2^3 x 1 + 2^2 x 0 + 2^1 x 0 + 2^0 x 0
So, 10002 = 8
Therefore, The number 1000_2 is equivalent to decimal number is 810.

S6. Ans.(c)
Sol. Ideal current source has internal resistance in parallel to it and its value is infinity so that no current could flow through the internal resistance branch and all of the current is supplied to the load.
The output resistance of CB transistor is very high so that no emitter current is lost and current obtained at load of transistor is approx. equal to emitter current.
This characteristics of CB configuration BJT is similar to that of ideal current source. Both can supply all current to the load.

S7. Ans.(a)
Sol. Input-output relation y(n) = x^2(n) does not satisfy the superposition and homogeneity property. If degree of output or input function is other than 1 then system generally behaves as non-linear. Hence, it is non-linear.

S8. Ans.(b)

S9. Ans.(c)

S10. Ans.(d)
Sol: The turn off time of a thyristor is the time between the instant when anode current becomes zero and the instant when the thyristor regains forward blocking capability. So, it depends on the forward current and also junction temperature. During turn off time, excess minority carriers from all the four layers of the thyristor must be removed.

Quiz Electronics Engineering 24 Oct 2020

Quiz Electronics Engineering
Exam: NIC
Topic: Miscellaneous
Date: 24/10/2020

Each Question carries 1 Mark
Negative Marking: 1/4
Time: 10 Minutes

Q1. To deliver a message to the correct application program running on a host, the _______ address must be consulted.
(a) IP
(b) Port
(c) MAC
(d) None of the above

Q2. An a.c series circuit has R = 6 Ω,X_L=20 Ω and X_C=12Ω. The circuit power factor will be
(a) 0.8 Leading
(b) 0.5 Lagging
(c) 0.6 Leading
(d) 0.6 Lagging

Q3. In 8085 to disable the whole interrupt(except TRAP):
(a) the interrupt instruction may be used
(b) the SI instruction may be used.
(c) the DI instruction may be used.
(d) the EI instruction may be used

Q4. The main factor that determines the accuracy of a reconstructed PCM signal is the
(a) number of bits used for quantization
(b) pulse repetition rate
(c) pulse amplitude
(d) Signal bandwidth

Q5. The number 1000_2 is equivalent to decimal number
(a) one thousand
(b) eight
(c) four
(d) sixteen

Q6. Which of the following device has characteristics closed to that of an ideal current source?
(a) Gas diode
(b) Crystal diode
(c) Transistor in CB mode
(d) All of the above

Q7. Which one of the following systems described by the following input-output relations is non-linear?
(a) y(n) = x^2(n)
(b) y(n) = x(n^2)
(c) y(n) = n^2x(n)
(d) y(n) = nx(2n)

Q8. Match List-I(Electromagnetic Law) with List-II(Differential Form) and select the correct answer using codes given below the lists:
List-I List-II
A. Ampere’s Law 1. ∇.D ⃗ = ρ_v
B. Faraday’s Law 2. ∇.J ⃗ = -(∂H ⃗)/∂t
C. Gauss Law 3. ∇ × H ⃗ = J ⃗ + (∂D ⃗)/∂t
D. Current Continuity equation 4. ∇ × E ⃗ = -(∂B ⃗)/∂t
Codes:
A B C D
(a) 1 2 3 4
(b) 3 4 1 2
(c) 1 4 3 2
(d) 3 2 1 4

Q9. Which of the following addressing mode is not usable in XCH instruction of 8085 microprocessor?
(a) Direct Addressing
(b) Indirect Addressing
(c) Immediate Addressing
(d) Register Addressing

Q10. Turn-off time of a thyristor is
(a) depends on load
(b) depends upon junction temperature
(c) depends upon forward current
(d) both (b) and (c)

SOLUTIONS

S1. Ans.(b)
Sol.
IP address tells about the location of the network.
MAC address is a unique address for every device.
Port address identifies a process or service which are to be carried to the device present at the destination.

S2. Ans(d)
Sol.
Z=√(6^2+(20-12)²) = 10
ϕ= R/Z = 6/10 = 0.6 lagging

S3. Ans.(c)
Sol. Destination Index(DI) instruction will disable all the instructions except TRAP.

S4. Ans.(a)
Sol. In PCM signal, quantization noise depends only on the number of bits used for quantization.
Qe = Δ/2 = (Dynamic Range)/(2.2^n )
Therefore, The main factor that determines the accuracy of a reconstructed PCM signal is number of bits used for quantization.

S5. Ans.(b)
Sol. Here,
⇒ 10002 = 2^3 x 1 + 2^2 x 0 + 2^1 x 0 + 2^0 x 0
So, 10002 = 8
Therefore, The number 1000_2 is equivalent to decimal number is 810.

S6. Ans.(c)
Sol. Ideal current source has internal resistance in parallel to it and its value is infinity so that no current could flow through the internal resistance branch and all of the current is supplied to the load.
The output resistance of CB transistor is very high so that no emitter current is lost and current obtained at load of transistor is approx. equal to emitter current.
This characteristics of CB configuration BJT is similar to that of ideal current source. Both can supply all current to the load.

S7. Ans.(a)
Sol. Input-output relation y(n) = x^2(n) does not satisfy the superposition and homogeneity property. If degree of output or input function is other than 1 then system generally behaves as non-linear. Hence, it is non-linear.

S8. Ans.(b)

S9. Ans.(c)

S10. Ans.(d)
Sol: The turn off time of a thyristor is the time between the instant when anode current becomes zero and the instant when the thyristor regains forward blocking capability. So, it depends on the forward current and also junction temperature. During turn off time, excess minority carriers from all the four layers of the thyristor must be removed.

Quiz Electronics Engineering 23 Oct 2020

Quiz Electronics Engineering
Exam: NIC
Topic: Miscellaneous
Date: 23/10/2020

Each Question carries 1 Mark
Negative Marking: 1/4
Time: 10 Minutes

Q1. After counting 0, 1, 10, 11 the next binary number is
(a) 15
(b) 100
(c) 110
(d) 120

Q2. Maximum theoretical conversion efficiency of a transformer coupled class-A amplifier is typically
(a) 90%
(b) 75%
(c) 50%
(d) 25%

Q3. Consider a complex exponential sequence ω_o. Suppose ω_o = 2π, then
(a) such a sequence is periodic.
(b) such a sequence is not periodic at all
(c) periodic for some value of period ‘N’
(d) some definite range N_o < n < N_1 exists for a periodic sequence

Q4. Which of the following is a unipolar device?
(a) P-N junction diode
(b) Zener diode
(c) Tunnel diode
(d) Schottky diode

Q5. A variable reluctance stepper motor is constructed of ______________ material with salient poles.
(a) Paramagnetic
(b) Ferromagnetic
(c) Diamagnetic
(d) Non-magnetic

Q6. CRC stands for __________
(a) code redundancy check
(b) code repeat check
(c) Cyclic Redundancy Check
(d) cyclic repeat check

Q7. In a microprocessor, the register which holds the address of the next instructions to be fetched is:
(a) Program Counter
(b) Accumulator
(c) Stack Pointer
(d) Instruction Register

Q8. Charge needed within a unit sphere centered at the origin for producing a potential field, V=-6r5∈_O , for r ≤ 1 is
(a) 60π C
(b) 12π C
(c) 180π C
(d) 120π C

Q9. The output waveform of a 555 Timer is:
(a) Sinusoidal
(b) Triangular
(c) Rectangular
(d) Elliptical

Q10. To separate channels in FDM receiver we have to use
(a) integration
(b) band pass filter
(c) AND gate
(d) differentiation

SOLUTIONS

S1. Ans (b)
Sol. The sequence is as following:
⇒ 02 = 010
⇒ 12 = 110
⇒ 102 = 210
⇒ 112 = 310
⇒ 1002 = 410

S2. Ans.(c)
Sol. Conversion efficiency is
% η = (1-V_min/V_CC ) × 50 %
Maximum efficiency in class A amplifier is 50% in case of transformer coupled Class – A amplifier.

S3. Ans.(a)
Sol. In any complex exponential sequence,
⇒ h(n) = e^(jω_o n)
Period is –
⇒ N = 2π/ω_o .m where, m is integer
⇒ N = 2π/2π.m
⇒ N =m
For any integer value of m, N is rational. So, sequence is periodic.

S4. Ans.(d)
Sol. Schottky diode is a unipolar device because current conduction takes place only in one direction due to majority charge carrier either electrons or holes. This class of diodes use metal-to-semiconductor junction for rectification purposes instead of PN-junctions.

S5. Ans (b)
Sol. A Variable-reluctance Stepper motor is constructed of a soft iron multi-toothed rotor, a wound stator and ferromagnetic material with salient poles. The stator is made from a stack of steel laminations and has six equally-spaced projecting poles (or teeth) each wound with an exciting coil. Rotation occurs when the rotor teeth are attracted to the energized stator poles.

S6. Ans.(c)
Sol. A Cyclic Redundancy Check (CRC) is an error-detecting code used in digital networks and storage devices to detect accidental changes to raw data. It is inserted into the frame trailer i.e. a data, to identify any error that occurred during the transmission of the data. It only detects error but do not correct them.

S7. Ans.(a)
Sol. Program Counter is used to hold the memory address of the next instruction to be fetched for execution. It is an automatic counter which increases the address of the memory when execution is completed.

S8. Ans.(d)
Sol. Given:
V=-(6r^5)/∈_O
We know that,
E = -dV/dr
and, in case of charge with in a unit sphere( i.e. r = 1)
E = 1/(4π∈_O ) . q/r^2
Now,
E = -dV/dr = (30r^4)/∈_O
and 1/(4π∈_O ) . q/r^2 = (30r^4)/∈_O
⇒ 1/4π . q/1 = 30/1 [ for r = 1]
So, q =120π Coulomb.

S9. Ans.(c)
Sol. IC555 timer is used to generate Square Wave & Pulse signal which may be rectangular in shape.

S10. Ans.(b)
Sol. Channels are separated in FDM with the help of Bandpass filters.
Band pass filter allows a band of frequencies to pass through and attenuates other frequencies.

Quiz Electronics Engineering 22 Oct 2020

Quiz Electronics Engineering
Exam: NIC
Topic: Miscellaneous
Date: 22/10/2020

Each Question carries 1 Mark
Negative Marking: 1/4
Time: 10 Minutes

Q1. The first line of HTTP request message is called _________
(a) Request line
(b) Header line
(c) Status line
(d) Entity line

Q2. The number of doped regions in P-N diode is
(a) 1
(b) 2
(c) 3
(d) 4

Q3. Which instruction of 8051 microcontroller is used for reading data from code memory?
(a) MOV
(b) MOV X
(c) MOV C
(d) XCH

Q4. The effect of current shunt feedback in an amplifier is to
(a) increase the input resistance and decrease the output resistance.
(b) increase both input and output resistances.
(c) decrease both input and output resistances.
(d) decrease the input resistance and increase the output resistance

Q5. The value of a resistor creating thermal noise is doubled. The noise power generated is
(a) unchanged
(b) quadrupled
(c) doubled
(d) halved

Q6. A 4-bit synchronous counter uses flip-flops with propagation delay time of 25 ns each. The maximum possible time required for change of state will be
(a) 75 ns
(b) 50 ns
(c) 25 ns
(d) 100 ns

Q7. Which of the following is a transport layer protocol?
(a) Internet Control Message Protocol
(b) Stream Control Transmission Protocol
(c) Neighbor Discovery Protocol
(d) Dynamic Host Configuration Protocol

Q8. Assertion(A): There are no convergence issues with the discrete time Fourier Series in general.
Reason(R): A discrete time signal is always obtained by sampling a continuous time signal.
(a) Both A and R are True and R is the correct explanation of A.
(b) Both A and R are True but R is not the correct explanation of A.
(c) A is True but R is False.
(d) A is False but R is True.

Q9. Which of the following can be used as switching elements in SMPS?
(a) BJT
(b) MOSFET
(c) Both BJT and MOSFET
(d) Diodes

Q10. Method of image is applicable to which fields?
(a) Electrodynamic fields only.
(b) Electrostatic fields only.
(c) Neither electrostatic field nor electrodynamic field.
(d) Both electrostatic and electrodynamic fields.

SOLUTIONS

S1. Ans.(a)
Sol. The start line or the initial part of HTTP(Hyper Text Transfer Protocol) is called as Status Line. It is followed by request line and finally the header line of the response message. The first line of HTTP request message is called Request Line.

S2. Ans. (b)
Sol. The number of doped regions in PN diode is 2. Left side is doped with P-type material and right side is doped with N-type material.

S3. Ans.(c)
Sol. ‘MOV C’ instruction is used for reading data from code memory.

S4. Ans.(d)
Sol. Feedback current is given to the input from the output current sampling so it reduces the input resistance and increases the output resistance.

S5. Ans.(a)
Sol. It is given that the value of a resistor creating thermal noise is doubled.
We know that, Thermal noise Power is
• N = kTB
where,
k = 1.38 x 10-23 J/K is Boltzman Constant
T is temperature in kelvin
B is Bandwidth
It means thermal noise is independent from the resistor creating thermal noise.
Therefore, The noise power generated is unchanged.

S6. Ans(c)
Sol. In Synchronous Counter, clock is given to all the flipflops at the same time because all are synchronized. Hence, Time required for change of state is equal to the propagation delay time.
Therefore, The maximum possible time required for change of state will be 25ns.

S7. Ans.(b)
Sol. The Stream Control Transmission Protocol (SCTP) is a transport layer protocol. It is a unicast connection oriented protocols that ensures reliable, in-sequence transport of data. used in networking system where streams of data are to be continuously transmitted
between two connected network nodes. Some of the other transport layer protocols are TCP, UDP etc.

S8. Ans.(d)
Sol. Region of convergence is an important parameter in Fourier Series because Discrete Time Fourier Series exist only for convergent signals.

S9. Ans.(c)
Sol. Both BJT and MOSFET are used as switching elements in SMPS. But MOSFET is preferred over BJT.

S10. Ans.(b)

Quiz Electronics Engineering 20 Oct 2020

Quiz Electronics Engineering
Exam: NIC
Topic: Miscellaneous
Date: 20/10/2020

Each Question carries 1 Mark
Negative Marking: 1/4
Time: 10 Minutes

Q1. Which of the following has the highest priority?
(a) INTR
(b) RST 6.5
(c) RST 7.5
(d) TRAP

Q2. In the case of a 70–MHz IF carrier for a transponder bandwidth of 36 MHz, energy must lie between(in MHz):
(a) 34 and 106
(b) 52 and 88
(c) 106 and 142
(d) 34 and 142

Q3. Assertion(A): Capacitance between two parallel plates area ‘A’ each and distance of separation ‘d’ is εA/d for large A/d ratio.
Reason(R): Fringing electric field can be neglected for large A/d ratio.
(a) Both A and R are True and R is the correct explanation of A.
(b) Both A and R are True but R is not the correct explanation of A.
(c) A is True but R is False.
(d) A is False but R is True.

Q4. A continuous time system will be BIBO stable if all the eigen values are
(a) one
(b) distinct and their real parts negative
(c) negative
(d) zero

Q5. The phase controlled rectifiers used in speed control of DC motors converts fixed AC supply voltage into ___________ output voltage.
(a) variable frequency AC
(b) full rectified DC
(c) variable AC
(d) variable DC

Q6. Find out the integrating type analog to digital converter?
(a) Flash type converter
(b) Dual slope ADC
(c) Counter type converter
(d) Tracking converter

Q7. The underlying Transport layer protocol used by SMTP is ________
(a) Either TCP or UDP
(b) UDP
(c) TCP
(d) IMAP

Q8. The resistance of insulations, in general, _____________ with temperature rise.
(a) Decreases
(b) Increases rapidly
(c) Increases slowly
(d) Does not change

Q9. Which instruction is one byte instruction?
(a) JMP
(b) SHLD
(c) SPHL
(d) XRI

Q10. Kirchhoff’s current law is applicable to only
(a) closed loops in a network
(b) junction in a network
(c) electric circuits
(d) electronic circuits

SOLUTIONS

S1. Ans.(d)
Sol. Priority in decreasing order is –
⇒ TRAP > RST 7.5 > RST 6.5 > RST 5.5 > INTR

S2. Ans. (b)
Sol. Given:
• IF = 70 MHz
• BW = 36 MHz
Now,
fmin = 70 -18 = 52 MHz
So, fmax = 70 + 18 = 88 MHz

S3. Ans.(a)

S4. Ans.(c)
Sol. For a continuous time system to be BIBO the roots must lie to the left side of s-plane. Hence, roots are negative and so is the eigen values.

S5. Ans.(d)

S6. Ans.(b)
Sol. Other than dual slope ADC the rest belongs to direct type ADCs.

S7. Ans.(c)
Sol. Simple Mail Transfer Protocol (SMTP) as internet standard uses only reliable Transport protocol. TCP is a reliable protocol and is more appropriate because it ensures that every packet is delivered.

S8. Ans.(a)
Sol. The insulators have Negative temperature co-efficient so the resistances of insulations in general decreases with temperature rise. Insulators starts to conduct if temperature is increased more and more and conductance & resistance are inversely related.

S9. Ans.(c)
Sol. Number of bytes required by each instruction is –
• SPHL is 1 byte.
• SHLD is 3 bytes.
• JMP is 3 bytes
• XRI is 2 byte.

S10. Ans.(b)
Sol. Kirchhoff’s Current law state that at any node of an electrical circuit, the sum of currents flowing into that node is equal to the sum of currents flowing out of that node. Node is also termed as Junction.

Quiz Electronics Engineering 19 Oct 2020

Quiz Electronics Engineering
Exam: NIC
Topic: Miscellaneous
Date: 19/10/2020

Each Question carries 1 Mark
Negative Marking: 1/4
Time: 10 Minutes

Q1. Which one of them is a transferred electron device?
(a) BARITT diode
(b) IMPATT diode
(c) Gunn diode
(d) Step recovery diode

Q2. To overcome the difficulty of race around condition which of the following flip-flop is used?
(a) JK flip-flop
(b) SR flip-flop
(c) D flip-flop
(d) Master-slave flip-flop

Q3. What type of integration is chosen to fabricate Integrated Circuits like Counters, multiplexers and Adders?
(a) Small Scale Integration (SSI)
(b) Medium Scale Integration (MSI)
(c) Large Scale Integration (LSI)
(d) Very Large Scale Integration (VLSI)

Q4. If x(t) is of finite duration and is absolutely integrable, then the “region of convergence” is
(a) entire s plane
(b) from σ = -∞ to σ = +1
(c) from σ = -1 to σ = +∞
(d) entire right half plane

Q5. Which memory has the highest storage capacity?
(a) Magnetic tape
(b) Magnetic disc
(c) Core memory
(d) Semiconductor memory

Q6. PAM signals are constructed by using a low pass filter of pass band slightly greater than base band to avoid aliasing. This avoids distortion
(a) True for flat top pulses
(b) True if law pass filter has sharp cut-off
(c) Flat top pulses introduce envelope delay
(d) Flat top pulses introduce amplitude distortion and delay

Q7. The SI unit of capacitance is
(a) mho
(b) farad
(c) weber
(d) ohm

Q8. DNS database contains _______
(a) name server records
(b) hostname-to-address records
(c) hostname aliases
(d) all of the above

Q9. A DC link chopper as compared to AC link is
(a) efficient
(b) less costly
(c) both (a) and (b)
(d) bulky

Q10. Consider the following statements relating the electrostatic and magnetostatic fields:
1. The relative distribution of charges on an isolated conducting body is dependent on the total charge of the body.
2. The magnetic flux through any closed surface is zero.
Which of these statements is/are correct?
(a) Both 1 and 2
(b) 1 only
(c) 2 only
(d) Neither 1 nor 2

SOLUTIONS

S1. Ans.(c)
Sol. A Gunn diode is a two-terminal semiconductor diode, with Negative Differential Resistance. It is also known as a Transferred Electron Device (TED).

S2. Ans.(d)
Sol. Master slave flip flop is a cascade of two flip flops in which the first one responds to the data input when the block is high whereas the second one responds to the output of the first one when the clock is low. Thus the final output change only when the clock is low when the data inputs are not effective. Thus the race around condition gets eliminated in this.

S3. Ans.(b)
Sol. Fabrication of ICs like counter, multiplexers and adders requires 30-300 gates per chip. Therefore, Medium Scale Integration is best suitable.

S4. Ans.(a)

S5. Ans.(b)
Sol. Magnetic disc has the highest storage capacity.

S6. Ans.(d)
Sol. In flat top pulses due to aperture effect amplitude distortion is found.

S7. Ans.(b)

S8. Ans.(d)
Sol. DNS(Domain Name System) is an application layer protocol for message exchange between clients and servers. It is a distributed database implemented in a hierarchy of name servers. It is a host name to IP address translation service i.e. mapping IP addresses with the hostname. DNS is a distributed database implemented in a hierarchy of name servers.

S9. Ans.(c)
Sol.
• In AC link Chopper, the voltage inversion takes place. The DC voltage is converted into AC with the help of an inverter. Obtained AC is passed through a step-down or step-up transformers. The output from the transformers is again converted into DC by a rectifier. AC link choppers are very bulky and occupy a large amount of space.
• DC chopper works on DC voltage. They work as a step up and step down transformers on DC voltage. DC choppers are more efficient, speed, less cost and optimized devices. They provide smooth control over the DC voltage.

S10. Ans.(a)
Sol. Magnetic flux inside a closed surface is zero because net charge inside the closed surface is zero.

Quiz Electronics Engineering 17 Oct 2020

Quiz Electronics Engineering
Exam: NIC
Topic: Miscellaneous
Date: 17/10/2020

Each Question carries 1 Mark
Negative Marking: 1/4
Time: 10 Minutes

Q1. Consider the function F(s) = 1/(s(s^2+3s+2)) where F(s) is Laplace Transform of function f(t). The initial value of f(t) is:
(a) 5
(b) 5/2
(c) 5/3
(d) 0

Q2. In a discrete time complex exponential sequence of frequency ω_o = 1, the sequence is
1. Periodic with period 2π/ω_o
2. Non-periodic
3. Periodic for some value of period N
Which of the above statements is/are correct?
(a) 1 only
(b) 2 only
(c) 3 only
(d) 1 and 3

Q3. Resonant converters are basically used to
(a) reduce the switching losses
(b) eliminates harmonics
(c) generates large peaky voltage
(d) convert a square wave into a sine wave

Q4. In which of the following applications usually tuned voltage amplifiers are not used?
(a) Television receivers
(b) Radio receivers
(c) Public address system
(d) All of the above.

Q5. The unit of conductivity is
(a) ohm/m
(b) mho/m
(c) ohm. m
(d) mho. m

Q6. Which one of the following is not a function of network layer?
(a) routing
(b) inter-networking
(c) congestion control
(d) error control

Q7. Microcontroller contains:
(a) Processor and Timers
(b) Processor and I/O devices
(c) Processor Memory Timers and I/O devices
(d) Processor only

Q8. The cumulative addition of the four binary bits (1 + 1 + 1 + 1) gives
(a) 100
(b) 111
(c) 1001
(d) 1111

Q9. When a semiconductor bar is heated at one end, a voltage across the bar is developed. If the heated end is positive, the semiconductor is
(a) p-type
(b) n-type
(c) intrinsic
(d) highly degenerate

Q10. Consider the following:
In a Parallel Plate Capacitor, let the charge be held constant while the dielectric material is replaced by a different dielectric. Consider
1. Stored energy.
2. Electric field intensity.
3. Capacitance.
Which of these changes?
(a) 1 only
(b) 1 and 2 only
(c) 2 and 3 only
(d) 1, 2 and 3

SOLUTIONS

S1. Ans.(d)
Sol. Given:
F(s) = 1/(s(s^2+3s+2))
Initial Value Theorem is –
⇒ f(0^+) = lim┬(t → 0 )⁡〖f(t)〗 = lim┬(s → ∞)⁡〖sF(s)〗
So, lim┬(t → 0 )⁡〖f(t)〗 = 0

S2. Ans.(b)
Sol. Given:
ω_o = 1
In a discrete time for complex exponential sequence to be periodic the period must be rational.
Here,
Period = 2π/ω_o = 2π
The value obtained is irrational so the discrete time complex exponential sequence is non-periodic.

S3. Ans.(a)
Sol. Resonant converters eliminate much of the switching losses encountered in Pulse Width Modulation (PWM) converters.

S4. Ans.(c)
Sol. Tuned voltage amplifiers are not used in Public address system.

S5. Ans.(b)
Sol. We know that,
Conductivity = 1/Resistivity=1/(ohm.m)
Hence, unit of conductivity is mho/m.

S6. Ans.(d)
Sol. In the OSI network model, network layer provides data routing paths for communications with different devices at different network i.e. inter-networking. It also helps in congestion control. Error and flow control is a function of the data link layer and the transport layer.

S7. Ans.(c)
Sol. Microcontroller contains Processor Memory Timers and I/O devices. I/O devices perform the operation based on the instruction stored in the memory.

S8. Ans.(a)
Sol. Converting each binary bit to decimal and then adding we get,
1 + 1 + 1 + 1 = 4
Converting back to binary digit we get,
4_10 = (0100)_2

S9. Ans.(b)
Sol. Highly doped semiconductor is called Degenerate Semiconductor. It may be of N – Type
or P – Type. Thermoelectric Phenomenon causes diffusion of flow of charge carriers from hot
to a cold part of a crystal.
Based on Thermoelectric Phenomenon, we get that –
The electron charge carriers present at the hot end of the semiconductor moves towards the cold end due to diffusion, creating negative excessive charge carriers on the cold contact. So, the heated end of the semiconductor becomes positive and it is called N – Type semiconductor.
In P – Type semiconductor holes are majority charge carriers so it takes part in diffusion. The heated end of the semiconductor is negative so it is of P – Type.

S10. Ans.(d)
Sol. We know that,
W_E = Q^2/2C
E = εD
C = Aε/d
All the three are proportional to dielectric material ε so when dielectric material changes these three value also changes.

Quiz Electronics Engineering 16 Oct 2020

Quiz Electronics Engineering
Exam: NIC
Topic: Miscellaneous
Date: 16/10/2020

Each Question carries 1 Mark
Negative Marking: 1/4
Time: 10 Minutes

Q1. What is the electric field when the voltage applied is 5V and the length is 100cm?
(a) 0.5V/m
(b) 5V/m
(c) 50V/m
(d) None of the above

Q2. What is the direction of data bus?
(a) Bi-directional
(b) Uni-directional out microprocessor
(c) Uni-directional into microprocessor
(d) Mixed direction i.e. some lines into microprocessor and some other out of microprocessor

Q3. As compared to BJT, a power MOSFET has
(a) higher switching losses and lower conduction loss
(b) lower switching losses and lower conduction loss
(c) lower switching losses and higher conduction loss
(d) higher switching losses and higher conduction loss

Q4. In the IPv4 addressing format the number of networks allowed under Class B addresses is
(a) 220
(b) 234
(c) 221
(d) 214

Q5. The dominant mode in a rectangular waveguide is TE10, because this mode has
(a) no attenuation
(b) the highest cut-off wavelength
(c) no cut-off
(d) no magnetic field component

Q6. Ampere-second is the unit of
(a) emf
(b) power
(c) electric charge
(d) energy

Q7. Modulation is the process of
(a) reducing distortion in RF amplifiers
(b) generating constant-frequency radio waves
(c) improving thermal stability of a transistor
(d) combining audio and radio frequency waves at the transmitting end of a communication system

Q8. The response of a linear, time-invariant, discrete-time system to a unit step input u(n) is the unit impulse 𝛿(n). The system response to a ramp input nu(n) would be
(a) u(n)
(b) u(n – 1)
(c) n𝛿(n)
(d) ■(∞@Σ@k=0) k𝛿(n – k)

Q9. The decimal equivalent of BCD 8421 number (10000000. 1001) is
(a) 128.56
(b) 128.9
(c) 80.25
(d) 128.25

Q10. Microprogramming refers to
(a) the use of storage to implement the control unit
(b) programming at micro level
(c) emulation
(d) array processing

SOLUTIONS

S1. Ans.(b)
Sol. Given:
Applied Voltage(V) =5V
length(L) = 100cm = 1m
Now,
E = V/L
⇒ E = 5/1
So, E = 5V/m.

S2. Ans.(a)
Sol. Data Bus is bi-directional and indicated by arrow in both direction. Data Bus is used to transfer data between microprocessor and memory and also between microprocessor and I/O devices. Same pins are used for data transfer.

S3. Ans.(c)
Sol. Power MOSFETS have lower switching losses but its ON-resistance and conduction losses are more. A BJT has higher switching loss but lower conduction loss. At higher frequency power MOSFET is better but at lower frequency BJT is superior.

S4. Ans.(d)
Sol. Class C has 16 network bits and 16 host bits.
Now, out of 16 network bits first 2-bits are reserved for Network ID i.e. “10” and remaining are 14 bits used for different networks. Therefore total number of networks possible are 214.

S5. Ans.(b)
Sol. TE10 is considered dominant mode because it has lowest cut off frequency which is equal to c/2a. We know that frequency is the inverse of wavelength i.e. (λ) = 1/f . As cut off frequency is minimum so it will have maximum wavelength.

S6. Ans.(c)
Sol. We know that,
⇒ I = q/t
⇒ q = I.t
So, Unit of electric-charge = Ampere–second.

S7. Ans (d)
Sol. Modulation is a process of varying amplitude, frequency or phase of carrier signal w.r.t modulating signal. So, It is the process of combining audio and radio frequency waves at the transmitting end of a communication system.

S8. Ans.(a)
Sol. The response of a linear, time-invariant, discrete-time system to a unit step input u(n) is the unit impulse 𝛿(n) that means the system acts as a Differentiator.
So, The system response to a ramp input nu(n) would be u(n).

S9. Ans(a)
Sol. Converting binary to decimal, we get
1 0 0 0 0 0 0 0 . 1 0 0 1 = 2^7 × 1 + 2^(-1) × 1 + 2^(-4) × 1
= 2^7 + 1/2 + 1/2^4
= 128 + 0.5 + 0.0625
= 128.5625
Therefore, (10000000. 1001)2 = 128.56

S10. Ans.(c)
Sol. Microprogramming consists of microcode with the help of which large number of architectures are achieved. It consists of large number of execution units and wider word lengths.

Quiz Electronics Engineering 15 Oct 2020

Quiz Electronics Engineering
Exam: NIC
Topic: Miscellaneous
Date: 15/10/2020

Each Question carries 1 Mark
Negative Marking: 1/4
Time: 10 Minutes

Q1. The hexadecimal number 64AC is equivalent to decimal number
(a) 25727
(b) 25722
(c) 25772
(d) 25277

Q2. The 8259A programmable interrupt controller in cascade mode can handle interrupts of:
(a) 64 priority level
(b) 32 priority level
(c) 16 priority level
(d) 8 priority level

Q3. Assertion(A): The system described by y^2(t) + 2y(t) = x^2(t) + x(t) + c is a linear and static system.
Reason(R): The dynamic system is characterized by differential equation.
(a) Both A and R are True and R is the correct explanation of A.
(b) Both A and R are True but R is not the correct explanation of A.
(c) A is True but R is False.
(d) A is False but R is True.

Q4.Which layer is not present in TCP/IP Model?
(a) Internet Layer
(b) Application Layer
(c) Session Layer
(d) Transport Layer

Q5. In a single-phase full converter, if load current is I and ripple free, then average thyristor current is
(a) 1/2 I
(b) 1/3 I
(c) 1/4 I
(d) I

Q6. The power consumption of LED is
(a) low
(b) very low
(c) Very high
(d) high

Q7. Which of the following scheme is a digital modulation technique?
(a) Pulse code modulation
(b) On-off keying
(c) Pulse width modulation and Delta modulation
(d)All of the above

Q8. Microprocessor 8085 can address location up to
(a) 32 K
(b) 64 K
(c) 128 K
(d) 1 M

Q9. Assertion(A): Even if two different approaches are used to solve Laplace equation, we will end up in the same direction.
Reason(R): It is mainly because in the process of solution, parameters relating to potentials and their spatial rates of change may assume different values.
(a) Both A and R are True and R is the correct explanation of A.
(b) Both A and R are True but R is not the correct explanation of A.
(c) A is True but R is False.
(d) A is False but R is True.

Q10. Which one of the following statements is correct?
In a four-branch parallel circuit, 50 mA current flows in the each branch. If one of the branches opens, the current in the other branches
(a) increase
(b) decrease
(c) are unaffected
(d) double

SOLUTIONS

S1. Ans. (c)
Sol.
(64 AC)16 = 6 × 163 + 4 × 162 + A × 161 + C × 160
= 6 × 163 + 4 × 162 + 10 × 161 + 12 × 160 [∵ A = 1010 & C = 1210]
= 6 × 4096 + 4 × 256 + 10 × 16 + 12 × 1
= 24576 + 1024 +160 +12
= 25772
Therefore, (64 AC)16 = 2577210

S2. Ans.(a)

S3. Ans.(d)
Sol. The system described above cannot be a linear system because it does not follow the superposition and homogeneity principle.

S4. Ans.(c)
Sol. The TCP/IP model was developed before the OSI model. This model is not exactly similar to the OSI model. The TCP/IP model consists of four layers:
the Application layer,
Transport layer or Host to Host Layer,
Internet layer
Network Access layer,

S5. Ans.(a)

S6. Ans.(b)
Sol. Light Emitting Diode (LED) has very low resistance so power consumption of LED is very low.

S7. Ans.(d)
Sol. Some of the Digital Modulation techniques are:-
Pulse Code Modulation,
ON-OFF Keying
Delta Modulation
Pulse Width Modulation
Pulse Position Modulation
Amplitude Shift Key and many others

S8. Ans.(b)
Sol. 8085 microprocessor has 16-bits address bus and 8-bit data bus lines.
No. of address locations = 2^16 = 64 KB address locations.

S9. Ans.(a)

S10. Ans.(c)
Sol. In Parallel circuit, the voltage across each branch is fixed and value of resistance is also fixed so current will not change on opening one of the branches.

Quiz Electronics Engineering 13 Oct 2020

Quiz Electronics Engineering
Exam: NIC
Topic: Miscellaneous
Date: 13/10/2020

Each Question carries 1 Mark
Negative Marking: 1/4
Time: 10 Minutes

Q1. If the number of inputs to a multiplexer are 32, the number of control signals needed are
(a) 4
(b) 5
(c) 6
(d) 8.

Q2. During the turn-off process of a thyristor the current flow does not stop at the instant when the current reaches zero but continues to flow to a peak value in the reverse direction. This is due to
(a) commutation failure
(b) hole storage effect
(c) presence of reverse voltage across the thyristor
(d) protective inductance in series with the thyristor

Q3. The resistivity of semiconductor lies in between
(a) 10-4 to 0.1 Ω-m
(b) 10-4 to 0.2 Ω-m
(c) 10-4 to 0.1 Ω-m
(d) 10-4 to 0.5 Ω-m

Q4. A function of one or more variables which conveys information on the nature of physical phenomena is called
(a) Signal
(b) Interference
(c) system
(d) Noise

Q5. In which of the following version of computer, microprocessor was used?
(a) First generation
(b) Fourth generation
(c) Third generation
(d) Second generation

Q6. Which one of the following statements is correct?
(a) Both Laplace’s and Poisson’s equations are non-linear equations.
(b) Laplace’s equation is non-linear but Poisson’s equation is linear.
(c) Laplace’s equation is linear but Poisson’s equation is non-linear.
(d) Both Laplace’s and Poisson’s equations are linear equations.

Q7. Minimum number of flip-flops needed to construct a BCD decode counter is
(a) 4
(b) 3
(c) 10
(d) None of these

Q8. A series R-C circuit having R = 5 Ω and C = 100 μF has a time constant of
(a) 20 μsec
(b) 5 × 10^(-4) s
(c) 0.005 s
(d) 500 s

Q9. The bandwidth required for base band signals for FM radio is generally
(a) 0.3 to 3 kHz
(b) 0.5 to 1.5 kHz
(c) up to 15 kHz
(d) up to 15 MHz

Q10. In File Transfer Protocol, data transfer cannot be done in ___________
(a) message mode
(b) block mode
(c) compressed mode
(d) stream mode

SOLUTIONS

S1. Ans (b)
Sol. In 2^m : 1 MUX, 2^m denotes the number of input lines and m is the number of control signal needed to select any particular input lines.

S2. Ans.(d)

S3. Ans.(d)
Sol. Resistivity of a semiconductor material lies in between an insulator and conductor i.e. 10^(-4) to 0.5 Ω-m.

S4. Ans.(a)

S5. Ans.(b)
Sol. Microprocessor was used during the 4th generation between 1971 – 1980. In this generation, VLSI(Very Large Scale integration) is used.

S6. Ans.(c)

S7. Ans(a)
Sol. For representing a number, BCD decade counter uses four binary number and each flip flop used in counter gives the output as one binary number so minimum 4 flip-flops are required.

S8. Ans.(b)
Sol. Time constant is
τ = RC = 5 × 100 × 10^(-6)= 5 × 10^(-4) sec.

S9. Ans.(c)
Sol. The frequency band for FM radio is about 88 to 108 MHz. The information signal is music and voice which falls in the audio spectrum. The full audio spectrum ranges from 20 to 20,000 Hz, but FM radio limits the upper modulating frequency to 15 kHz

S10. Ans.(a)
Sol. FTP(File Transfer Protocol) defines three different transmission modes that specify exactly how data is sent from one device to another over an opened data channel, Transmission mode is also called transfer modes. Those are –
Stream mode: In this data is transferred simply as a continuous stream of unstructured bytes.
Block mode: In this mode data is transferred after being broken into data blocks and encapsulated into individual FTP blocks, or records.
Compressed mode: In this mode data is transferred after being compressed

Quiz Electronics Engineering 12 Oct 2020

Quiz Electronics Engineering
Exam: NIC
Topic: Miscellaneous
Date: 12/10/2020

Each Question carries 1 Mark
Negative Marking: 1/4
Time: 10 Minutes

Q1. In an SSB transmitter one is most likely to find
(a) Class-C audio amplifier
(b) Tuned modulator
(c) Class-B RF amplifier
(d) Class-AB power amplifier

Q2. Secondary breakdown does not occur in
(a) MOSFET but occurs in BJT
(b) Both MOSFET and BJT
(c) BJT but occurs in MOSFET
(d) None of the above

Q3. The resistance between points A and B as shown in figure will be

(a) 100 Ω
(b) 150 Ω
(c) 250 Ω
(d) 300 Ω

Q4. For the circuit shown in Fig. the value of input for Y = 0 is

(a) 00
(b) 10
(c) 01
(d) 11

Q5. To which one of the following difference equations, the impulse response h(n) = 𝛿(n + 2) – 𝛿(n – 2) corresponds?
(a) y(n + 2) = x(n) – x(n – 2)
(b) y(n – 2) = x(n) – x(n – 4)
(c) y(n) = x(n + 2) + x(n – 2)
(d) y(n) = -x(n + 2) + x(n – 2)

Q6. Which flag does not change by the execution of the instruction DCR B in 8085 microprocessor?
(a) Parity
(b) Zero
(c) Carry
(d) Sign

Q7. A charge of 1 C is placed near a grounded conducting plate at a distance of 1 m. What is the force between them?
(a) 1/(16πε_o ) N
(b) 1/(8πε_o ) N
(c) 1/(4πε_o ) N
(d) 4πε_o N

Q8. The DHCP server can provide the _______ of the IP addresses.
(a) dynamic allocation
(b) automatic allocation
(c) static allocation
(d) all of the above

Q9. An intrinsic semiconductor has the following properties:
1. Its electron concentration equals its hole concentration.
2. Its carrier density increases with temperature.
3. Its conductivity decreases with temperature.
Which of these statements are correct ?
(a) 1, 2 and 3
(b) 2 and 3 only
(c) 1 and 2 only
(d) 1 and 3 only

r

Q10. If in the below given figure resistor R_3 become open circuited, the voltmeter will read

(a) Zero
(b) 62.5 V
(c) 125 V
(d) 250 V

SOLUTIONS

S1. Ans.(c)
Sol. In SSB carrier is suppressed. So, Class B- RF amplifier is enough to amplify RF signal.

S2. Ans.(a)
Sol. Secondary breakdown is a failure mode in BJT because it has Negative Temperature Coefficient. In it negative resistance (current concentration) occurs under high-voltage and high-current conditions. MOSFET has Positive Temperatures Coefficient so no secondary breakdown in it.

S3. Ans.(b)
Sol. No current flows through the encircled branch.

⇒ RAB = 50 + 50 + (100 × 100)/(100 + 100)
⇒ RAB = 100 + 10000/200 = 150 Ω
So, RAB = 150 Ω

S4. Ans (d)
Sol. If A =1 and B = 1. Then Y = 1.

S5. Ans.(b)
Sol. Given:
h(n) = 𝛿(n + 2) – 𝛿(n – 2)
We know that,
x(n)*𝛿(n – n_o) □(↔┴( F.T ) ) x(n – n_o)
Here,
y(n) = x(n)*h(n)
⇒ y(n) = x(n)* 𝛿(n + 2) – 𝛿(n – 2)
⇒ y(n) = x(n + 2) – x(n – 2)
and y(n – 2) = x(n) – x(n – 4)

S6. Ans.(c)
Sol. ‘DCR B’ means the contents of the B register is decremented by ‘1’. Except carry flag, all the flag change due to this instruction. Carry Flag is set when carry is generated in 8085 microprocessor.

S7. Ans.(a)
Sol. Using the method of image charge.
A charge of 1 C is placed near a grounded conducting plate at a distance of 1 m so a similar but opposite charge is placed at a distance of 1 m below the conducting plate.
Distance between the two charges = 2 m
From Coulomb’s Law
F = (Q_1 Q_2)/(4πε_0 r^2 )
Now,
F = ( 1 × 1 )/(4πε_0 (2^2))
So, F = 1/(16πε_0 )

S8. Ans.(d)

S9. Ans.(c)
Sol. Conductivity of intrinsic semiconductor increases with temperature.

S10. Ans.(d)
Sol. As Voltmeter has very high internal resistance circuit so when R_3 become open circuited no current flow through voltmeter and thus circuit acts as Open Circuit. No current flow in the circuit so no voltage drop across any resistance hence voltage across the voltmeter is Supply Voltage i.e. 250 Volts.

Quiz Electronics Engineering 10 Oct 2020

Quiz Electronics Engineering
Exam: NIC
Topic: Miscellaneous
Date: 10/10/2020

Each Question carries 1 Mark
Negative Marking: 1/4
Time: 10 Minutes

Q1. A FET can be used as a variable
(a) inductor
(b) capacitor
(c) resistor
(d) voltage source

Q2. In a weighted-resistor digital-to-analog converter with 8-bit input, if the resistance corresponding to the MSB is 2kΩ, what will be the resistance corresponding to the LSB?
(a) 250 kΩ
(b) 256 kΩ
(c) 512 kΩ
(d) 25.5 kΩ

Q3. The impulse response of a system is h(t) = 𝛿(t – 0.5). If two such systems are cascaded, the impulse response of the overall system will be
(a) 𝛿(t – 1)
(b) 𝛿(t – 0.25)
(c) 0.5𝛿(t – 0.25)
(d) 0.5𝛿(t – 1)

Q4. A 1 μF capacitor is connected to 12 V battery. The energy stored in the capacitor is:
(a) 12×10^(-6) J
(b) 24×10^(-6) J
(c) 48×10^(-6) J
(d) 72×10^(-6) J

Q5. Thyristor is a semiconductor switch which is
(a) unilateral and astable
(b) bilateral and bistable
(c) unilateral and bistable
(d) bilateral and astable

Q6. Personal computer’s Basic Input Output System(BIOS) is present in –
(a) RAM chips
(b) magnetic tapes
(c) registers
(d) ROM chips

Q7. De-emphasis circuit is used
(a) before detection
(b) after detection
(c) before modulation
(d) after modulation

Q8. The property of Fourier Transform which states that the compression in time domain is equivalent to expansion in the frequency domain is
(a) duality
(b) frequency shifting
(c) scaling
(d) time scaling

Q9. If the potential functions V_1 and V_2 satisfy Laplace’s equation with in a closed region and assume the same values on its surface, then which of the following is correct?
(a) V_1 and V_2 are identical.
(b) V_1 is inversely proportional to V_2 .
(c) V_1 has the same direction as V_2.
(d) V_1 has the same magnitude as V_2 but has different direction.

Q10. Which of the following is a MAC address?
(a) 192.166.200.50
(b) 00056A:01A01A:5CCA7F:F60
(c) 01 : A5 : BB : A7: FF : 60
(d) 568

SOLUTIONS

S1. Ans. (c)
Sol. Small Signal FET drain resistance varies with applied gate-source voltage V_GS and so FET acts like a Voltage Variable Resistor.

S2. Ans.(b)
Sol. Given:
Resistance corresponding to the MSB = 2kΩ
Number of bits(n) = 8
We know that, Resistance corresponding to LSB is
R_LSB=R_MSB×2^(n-1)
⇒ R_LSB = 2 × 2^(8-1)
⇒ R_LSB = 2^8 kΩ
So, R_LSB = 256 kΩ

S3. Ans.(a)
Sol. According to the property of Impulse response –
𝛿(t – a)* 𝛿(t – b) = 𝛿(t – a – b)
Here, When the system is cascaded, the overall impulse response is –
⇒ 𝛿(t – 0.5)* 𝛿(t – 0.5) = 𝛿(t – 0.5 – 0.5)
So, 𝛿(t – 0.5)* 𝛿(t – 0.5) = 𝛿(t – 1)

S4. Ans. (d)
Sol. Given:
V = 12 volts
C = 1 μF = 10^(-6) F
We know that Energy stored in the capacitor is
⇒ W =1/2 CV^2
⇒ W = 1/2 × 12^2 × 10^(-6) J
⇒ W = 1/2 × 144 × 10^(-6) J
So, W = 72 × 10^(-6) J

S5. Ans.(c)
Sol. A thyristor is a solid-state semiconductor device having four layers. P- and N-type materials are arranged alternately. It acts exclusively as a bistable switch, conducting when the gate receives a current trigger, and continuing to conduct until the voltage across the device is reversed biased, or until the voltage is removed (by some other means). Thyristor also called SCR is a unidirectional device i.e. Unilateral. It has three modes of operation. Those are-
1. Forward conduction mode
2. Forward blocking mode
3. Reverse blocking mode
First two are stable states so, it is called Bistable.

S6. Ans.(d)
Sol. BIOS is present in the ROM chip of Personal Computer. It is a firmware which initialize the booting process when the system is turned ON.

S7. Ans (b)
Sol. De-emphasis means attenuating those frequencies by the amount by which they are boosted. It will be done in the receiver side after demodulation i.e., after detection.

S8. Ans.(d)
Sol. In Time Scaling,
x(at) ↔┴( F.T ) 1/|a| X(f/a)

S9. Ans.(a)

S10. Ans.(c)
Sol. The standard format of MAC contains 48 bits. Each 4 bits is represented in hexadecimal format i.e. 12 hexadecimal numbers in group, each contains 2 hexadecimal number and each separated by : or – or ;
So, 01 : A5 : BB : A7 : FF : 60 is a MAC address.

Quiz Electronics Engineering 9 Oct 2020

Quiz Electronics Engineering
Exam: NIC
Topic: Miscellaneous
Date: 09/10/2020

Each Question carries 1 Mark
Negative Marking: 1/4
Time: 10 Minutes

Q1. Assertion(A): The expression E ⃗ = -∇V, where E ⃗ is the electric field and V is the potential is not valid for time varying fields.
Reason(R): The curl of a gradient is identically zero.
(a) Both A and R are True and R is the correct explanation of A.
(b) Both A and R are True but R is not the correct explanation of A.
(c) A is True but R is False.
(d) A is False but R is True.

Q2. What is the period of the sinusoidal signal x(n) = 5cos[0.2πn]?
(a) 0
(b) 5
(c) 1
(d) 10

Q3. The essential blocks of a Phase Locked Loop(PLL) are phase detector, amplifier
(a) High Pass Filter and Crystal Controlled Oscillator
(b) Low Pass Filter and Crystal Controlled Oscillator
(c) Low Pass Filter and Voltage Controlled Oscillator
(d) High Pass Filter and Voltage Controlled Oscillator

Q4. (1111.11)_2 is
(a) (1.01)_10
(b) -(0.75)_10
(c) (15.3)_10
(d) (15.75)_10

Q5. The property of a material to permit electric current to flow through it
(a) inductance
(b) conductance
(c) capacitance
(d) resistance

Q6. The total resistance between B and C will be

(a) 160/3 Ω
(b) 180/3 Ω
(c) 190/6 Ω
(d) 195/3 Ω

Q7. A local telephone network is an example of a _______ network.
(a) Packet switched
(b) Bit switched
(c) Circuit switched
(d) Line switched

Q8. The minimum number of flip-flops required for a mod- 14 counter is
(a) 6
(b) 4
(c) 8
(d) 16

Q9. What is the expression for capacitance of an infinitely conducting solid sphere of radius ‘R’ in free space?
(a) 2πε_oR
(b) 0.5πε_oR
(c) 8πε_oR
(d) 4πε_oR

Q10. Null character needs a space of
(a) 1 Bytes
(b) 4 Bytes
(c) 2 Bytes
(d) 0 Bytes

SOLUTIONS

S1. Ans.(a)

S2. Ans.(d)
Sol. Given:
x(n) = 5cos[0.2πn]
We know that, Time period of a discrete time signal is –
⇒ N = 2π/ω
Here,
ω = 0.2π
So, N = 2π/0.2π = 10

S3. Ans.(c)
Sol. The essential blocks of a Phase Locked Loop(PLL) are phase detector, amplifier, Low Pass Filter and Voltage Controlled Oscillator. When PLL is used as FM demodulator multiplier is replaced by phase detector.
Basic Block diagram of PLL detector :

S4. Ans.(d)
Sol. Converting binary to decimal, we get
(1111.11)_2 = 1×23 + 1×22 + 1×21 + 1×20 + 1×2-1 + 1×2-2
= 8 + 4 + 2 + 1 + 0.5 + 0.25
= 15.75
Therefore, (1111.11)_2 =〖 (15.75)〗_10

S5. Ans.(b)
Sol. With respect to the current flow, material has two basic properties one is to oppose the current flow called Resistance of the material and another one is to permit or pass the electric current, called Conductance of the material.

S6. Ans.(a)
Sol.

Since, 40Ω is connected in parallel with 20 Ω.
Here,
⇒ 1/R=1/40+1/20=3/40
So, R = 40/3 Ω

Total resistance across BC is
⇒ R_AB = 20+40/3+20
⇒ R_AB = (20×3+40+20×3)/3
⇒ R_AB = (60+40+60)/3
So, R_AB = 160/3 Ω

S7. Ans.(c)
Sol. In Packet Switching connectionless switching technique is used but in Circuit switching there is connection oriented switching technique. A Local Telephone network spreads in a local area to connect with the people with the help of wired medium. So, it is guided or connection oriented media.

S8. Ans (b)
Sol. Given:
Number of valid state(N) = 14
The number of flip-flops(n) required for a desired MOD number-N is found out using the equation:
Number of flip flop(n) = log_2⁡N
Now,
n = log_2⁡N
⇒ n = log_2⁡14
⇒ n = 3.80
But number of flip flop is always in natural number.
So, n = 4
Therefore, number of flip-flops is 4.

S9. Ans.(d)
Sol. We know that Q = CV
and Voltage of an infinitely conducting solid sphere of radius ‘R’ in free space is
V = Q/(4πε_0 R)
Now,
C = Q/V
⇒ C = Q/(Q/(4πε_0 R))
So, C = 4πε_0 R

S10. Ans.(a)
Sol. Null character doesn’t means empty. It means there is some character like “/0” or “/00” etc., which indicate that any data terminates there. To store it 1 byte space is required.

Quiz Electronics Engineering 8 October 2020

Quiz Electronics Engineering
Exam: NIC
Topic: Miscellaneous
Date: 08/10/2020

Each Question carries 1 Mark
Negative Marking: 1/4
Time: 10 Minutes

Q1. Fastest memory cell is –
(a) Bubble memory
(b) Semiconductor RAM
(c) Superconductor memory
(d) Semiconductor memory

Q2. Which one of the following must be satisfied if a signal is to be periodic for -∞ < t < ∞?
(a) x(t + T_o) = x(t)
(b) x(t + T_o) = dx(t)/dt
(c) x(t + T_o) = ∫_t^(T_o)▒〖x(t)〗dt
(d) x(t + T_o) = x(t) + kT_o

Q3. In the OSI model, as a data packet moves from the lower to the upper layers, headers are _______ .
(a) Rearranged
(b) Added
(c) Removed
(d) Random placement

Q4. A pn junction diode’s dynamic conductance is directly proportional to
(a) the applied voltage
(b) its current
(c) the thermal voltage
(d) the temperature

Q5. What is the value of Thevenin voltage V_Th in the given Thevenin’s equivalent circuit?

(a) 40V
(b) 45V
(c) 50V
(d) 35V

Q6. Which of the following processor structure is pipelined?
(a) 8086
(b) 8080
(c) 4040
(d) 8085

Q7. Assertion(A): Net charge within a conductor is always zero.
Reason(R): The conductor has a very large number of free electrons.
(a) Both A and R are True and R is the correct explanation of A.
(b) Both A and R are True but R is not the correct explanation of A.
(c) A is True but R is False.
(d) A is False but R is True.

Q8. After counting 0, 1, 10, 11 the next binary number is
(a) 15
(b) 110
(c) 100
(d) 120

Q9. If you have to send multimedia data over SMTP it has to be encoded into _______
(a) Binary
(b) Hash
(c) Signal
(d) ASCII

Q10. v(t) = 5[cos(106πt) – sin(103πt) x sin(106πt)] represents
(a) NBFM signal
(b) AM signal
(c) SSB upper sideband signal
(d) DSB-SC signal

SOLUTIONS

S1. Ans.(d)
Sol. Semiconductor memory is made up of flip-flop so both its access time and cycle time is very less. Hence, It is the fastest memory cell.

S2. Ans.(a)

S3. Ans.(c)
Sol. Header contains the control information and parameters agreed between the applications. It is only sent at the beginning of an operation. In OSI model, when data packet moves from lower layers to higher layer, headers get removed and vice versa.

S4. Ans.(b)
Sol. In a pn junction diode,
r = (ηV_T)/I
Transconductance = 1/resistance
So, g_m = I/(ηV_T )
Therefore, A pn junction diode’s dynamic conductance is directly proportional to its current.

S5. Ans.(d)
Sol. For calculating Thevenin voltage, load resistance is removed and calculated across AB.

where,
V_Th is Open circuit voltage at terminal AB
No current flows through DA branch due to open circuit. Net resistance is 10 Ω.
Current in open circuit is –
I = 50/10=5 A
So, Thevenin voltage is calculated across 7 Ω resistance.
⇒ V_Th = 5 × 7
So, V_Th = 35 volts

S6. Ans.(a)
Sol. 8086 microprocessor is a microprocessor which works on the pipeline technique. It works in two stages – Fetch Stage and Execution Stage.

S7. Ans.(b)
Sol. Both the statements are correct.
Net charge within a conductor is always zero because due to law of electrical charge neutrality.

S8. Ans (c)
Sol. The sequence is as following:
⇒ 02 = 010
⇒ 12 = 110
⇒ 102 = 210
⇒ 112 = 310
⇒ 1002 = 410

S9. Ans.(d)
Sol. Only 7-bit ASCII codes are transmitted through SMTP. So, it is mandatory to convert binary multimedia data to 7-bit ASCII before it is sent using SMTP.

S10. Ans.(a)
Sol.
Here,
v(t) = 5[cos(106πt) – sin(103πt) x sin(106πt)]
⇒ v(t) = 5cos(106πt) – 5/2cos(106 – 103) πt + 5/2cos(106 + 103) πt
From above expression of signal, we get that carrier and upper side band frequency components are in phase but the lower side band frequency component is out of phase.
Therefore, The given expression represents a NBFM signal.

Quiz Electronics Engineering 6 Oct 2020

Quiz Electronics Engineering
Exam: NIC
Topic: Miscellaneous
Date: 06/10/2020

Each Question carries 1 Mark
Negative Marking: 1/4
Time: 10 Minutes

Q1. If a circuit is at resonance, the applied voltage and resulting current are
(a) in phase
(b) out of phase by 90°
(c) out of phase by 270°
(d) out of phase by 180°

Q2. Maximum value of charging resistance in an UJT is associated with
(a) valley point
(b) peak point
(c) any point between peak and valley
(d) after the valley point

Q3. In a charge-free space, the Poisson equation results in which one of the following?
(a) Continuity equation
(b) Maxwell equation
(c) Laplace equation
(d) None of the above

Q4. Pretty good privacy (PGP) is used in ______
(a) Browser security
(b) Wi-Fi security
(c) FTP security
(d) Email security

Q5. Consider the following statements related to Fourier Series of a periodic waveform:
1. It expresses the given periodic waveform as a combination of DC component, sine and cosine waveforms of different harmonic frequencies.
2. The amplitude of spectrum is discrete.
3. The evaluation of fourier coefficients gets simplified if waveform symmetries are used.
4. The amplitude spectrum is continuous.
Which of the above statements are correct?
(a) 1, 2 and 3
(b) 2, 3 and 4
(c) 1, 3 and 4
(d) 1, 2 and 4

Q6. The device that generates the basic timing clock signal for the operation of the circuit using crystal oscillator is
(a) timing unit
(b) timing and control unit
(c) oscillator
(d) clock generator

Q7. In a low level AM transmitter, amplifier following the modulated stage must be
(a) class C amplifier
(b) linear devices
(c) non-linear devices
(d) harmonic devices

Q8. Secure shell network protocol is used for _________
(a) secure data communication
(b) remote command-line login
(c) remote command execution
(d) all of the above

Q9. Stack works on the principle of
(a) Last In First Out
(b) First In First Out
(c) Last In Last Out
(d) Random In Random Out

Q10. At resonant frequency a R-L-C series circuit draws maximum current due to the reason that
(a) the impedance is more than the resistance
(b) The difference between capacitance reactance and inductance reactance is zero.
(c) the voltage across the capacitor equals the applied voltage
(d) The power factor is less than unity

SOLUTIONS

S1. Ans.(a)
Sol. Since the current in the inductor and capacitor are 180 degrees out of phase of each other, the only current that flows in and out of the circuit is that of the resistor. In series circuits, current is the same through all components. At resonance, voltage across the resistor is in phase with the applied current.

S2. Ans.(b)

S3. Ans.(c)
Sol. Laplace Equation is
∇^2V = 0
Poisson Equation is
∇^2V = -ρ_v/ε
In charge free space region, ρ_v = 0
So, ∇^2V = 0
This is similar to Laplace equation.

S4. Ans.(d)
Sol. PGP is a data encryption computer program used in e-mail security to encrypt and decrypt texts, emails, and files which are to be transmitted over the internet to increase the security of emails.

S5. Ans.(a)

S6. Ans.(c)
Sol. The oscillator circuit generates the basic timing clock signal for the operation of the circuit using crystal oscillator.

S7. Ans.(b)
Sol. In a Low Level AM modulator the modulation is applied to low power stage of the transmitter. It is done in the RF generation stages, or via the digital signal processing areas. Linear amplification is required for the RF stages.

S8. Ans.(d)
Sol. SSH stands for Secure Shell. It is a cryptographic network protocol, used to access remote machine in order to execute command-line network services and other commands over a network. It is Known for its high security, cryptographic behavior and it is most widely used by network admins to control remote web servers primarily.

S9. Ans.(a)
Sol. In Stack, the data which is stored at last is at first moved out. So, the principle is called Last In First Out(LIFO).

S10. Ans.(b)
Sol. At resonance, impedance is minimum due to imaginary term of impedance Z is zero i.e. capacitive reactance is equal to inductive reactance. As impedance minimum so current flowing through a RLC circuit is maximum.

Quiz Electronics Engineering 4 Oct 2020

Quiz Electronics Engineering
Exam: NIC
Topic: Miscellaneous
Date: 04/10/2020

Each Question carries 1 Mark
Negative Marking: 1/4
Time: 10 Minutes

Q1. How many machine cycle are required for 3 byte instruction when executed with “STA 2065H”?
(a) 4
(b) 6
(c) 2
(d) 3

Q2. The values GET, POST, HEAD etc. are specified in ____________ of HTTP message
(a) Entity body
(b) Request line
(c) Status line
(d) Header line

Q3. The Boolean expression (A ̅+B)(A+C ̅)(B ̅+C ̅) Simplifies to
(a) (A+B)C ̅
(b) (A+B ̅)C ̅
(c) (A ̅+B)C ̅
(d) (A ̅+B ̅)C ̅

Q4. A network contains linear resistance and ideal voltage source. If the value of all the resistors are doubled, then the voltage across each resistor is:
(a) Halved
(b) Doubled
(c) Increased by four times
(d) Not changed

Q5. When a transistor is saturated,
(a) the base potential is more than the emitter-collector potential
(b) the emitter potential is more than the base-collector potential.
(c) the collector potential is more than the base-emitter potential.
(d) the base, emitter and collector are almost at the same potential.

Q6. For a given data rate, the bandwidth β_p of the BPSK signal and the bandwidth β_0 of the OQPSK signal are related as
(a) β_p=β_0/2
(b) β_p=2β_0
(c) β_p=β_0/4
(d) β_p=β_0

Q7. Which one of the following is correct? Energy of a power signal is
(a) finite
(b) zero
(c) infinite
(d) between 1 and 2

Q8. An electric charge Q is placed in a dielectric medium. Which of the following quantities are independent of the dielectric constant ε of the medium?
(a) Electric potential V and Electric Field Intensity E.
(b) Electric Potential V and displacement Ψ.
(c) Electric Field Intensity E and Displacement density D.
(d) Displacement density D and displacement Ψ

Q9. ICMP is primarily used for __________
(a) addressing
(b) routing
(c) forwarding
(d) error and diagnostic

Q10. ALE stands for
(a) Accumulator Logic Execution
(b) Arithmetic Logic Execution
(c) Address Latch Enable
(d) All enable

SOLUTIONS

S1. Ans.(a)
Sol. ‘STA 2065H’ means Store data directly from the Accumulator. The content present in the accumulator are stored in the memory location specified by 16-bit address in the operand.
bytes: 3
MC: 4
T-states: 13T

S2. Ans.(b)
Sol. A Request Line specifies the Method Token like GET, POST, HEAD etc. in the HTTP request message.

S3. Ans.(c)
Sol. (A ̅+B)(A+C ̅)(B ̅+C ̅)
=(A ̅A+A ̅C ̅+AB+BC ̅)(B ̅+C ̅)
= (A ̅C ̅+AB+BC ̅)(B ̅+C ̅) [ ∵ A ̅A = 0]
= A ̅B ̅C ̅ + ABB ̅ + BC ̅B ̅ + A ̅C ̅C ̅+ ABC ̅ + BC ̅C ̅
=A ̅B ̅C ̅+0+0+ A ̅C ̅+ABC ̅+BC ̅
=A ̅C ̅(B ̅+1)+(A+1)BC ̅
=A ̅C ̅+BC ̅ [ ∵ A + 1 = 1 & B ̅+1=1]
=(A ̅+B)C ̅

S4. Ans.(d)
Sol. On changing the values of linear resistors, there is change in the flow of current. So, both change in current and resistors cancel out each other. Hence, the voltage remains constant in case of ideal voltage source.

S5. Ans.(a)
Sol. In a Saturated region in transistor, both emitter-base and collector base are forward biased. So, the base potential is more than the emitter-collector potential.

S6. Ans.(b)
Sol. We know that,
For BPSK,
BW =2R_b = β_p ………….(1)
For OQPSK,
BW =R_b = β_0 ………….(2)
Comparing both (1) and (2), we get
⇒ β_p=2β_0

S7. Ans.(c)

S8. Ans.(d)
Sol.
∮▒〖D.ds〗 = Q_enclosed = Ψ
D = εE
V = ∫▒E ⃗ . (dl) ⃗
where,
Ψ is displacement
From above we can see that E, V, D and Ψ are related to each other.
Hence, we can tell Displacement density D and displacement Ψ are independent of the dielectric constant ε of the medium.

S9. Ans.(d)
Sol. ICMP stands for Internet Control Message Protocol. It is an internet layer protocol used by network devices like routers, to diagnose network communication issues. It is used to send error messages and operational information indicating success or failure when communicating with another IP address. It is a transport layer protocol in TCP/IP network model.

S10. Ans.(c)
Sol. Address Latch Enable(ALE) is used to select either address or data bus –
If ALE = 1, Address bus line is selected
otherwise for ALE = 0, Data bus line is selected.
Multiplexing and Demultiplexing of data bus line takes place.

Quiz Electronics Engineering 1 Oct 2020

Quiz Electronics Engineering
Exam: NIC
Topic: Miscellaneous
Date: 01/10/2020

Each Question carries 1 Mark
Negative Marking: 1/4
Time: 10 Minutes

Q1. Assertion(A): Potential everywhere on a conducting surface of infinite extent is zero.
Reason(R): Displacement density on a conducting surface is normal to the surface.
(a) Both A and R are True and R is the correct explanation of A.
(b) Both A and R are True but R is not the correct explanation of A.
(c) A is True but R is False.
(d) A is False but R is True.

Q2. In 8085 microprocessor, the value of the most significant bit of the result following the execution of any arithmetic of boolean instruction is stored in the
(a) carry status flag
(b) auxiliary carry status flag
(c) sign status flag
(d) zero status flag

Q3. In case of indirectly heated cathode, the cathode is usually in the shape of
(a) Cylinder
(b) Wire filament
(c) Metal strip
(d) Any of the above

Q4. Assertion(A): For a rational transfer function H(z) to be causal, stable and causally invertible both the zeros and the poles should lie within the unit circle in the z-plane.
Reason(R): For a rational system, ROC is bounded by poles.
(a) Both A and R are True and R is the correct explanation of A.
(b) Both A and R are True but R is not the correct explanation of A.
(c) A is True but R is False.
(d) A is False but R is True.

Q5. _______ topology requires a multipoint connection.
(a) Star Topology
(b) Mesh Topology
(c) Ring Topology
(d) Bus Topology

Q6. For the network shown in the figure, the value of current in 8 Ω resistor is

(a) 1.5 A
(b) 4.8 A
(c) 2.4 A
(d) 1.2 A

Q7. The advantage of serial data transfer compared to parallel data transfer is that
(a) it requires lesser number of wires
(b) it is faster
(c) it is more accurate
(d) it is more compatible

Q8. The pre-emphasis circuit is used
(a) after demodulation
(b) before demodulation
(c) to increase or emphasize the amplitude of low frequency components of signal
(d) None of these

Q9. TRAP is
(a) Maskable, lowest priority and hardware interrupt
(b) Maskable, highest priority and software interrupt
(c) Non-maskable, highest priority and software interrupt
(d) Non-maskable, highest priority and hardware interrupt

Q10. Which of the following protocol is used to File transfer from one machine to another?
(a) FTP
(b) SMTP
(c) HTTP
(d) Email

SOLUTIONS

S1. Ans.(b)
Sol. Conductor is an excellent equipotential surface so Potential everywhere on a conducting surface of infinite extent is zero. As EF is normal to the conducting surface so is the Displacement density D.

S2. Ans.(c)
Sol. The highest bit of any result after the execution of any arithmetic of boolean instruction will indicate the sign of the final result. This highest bit will act as sign status flag.

S3. Ans.(a)
Sol. In a directly heated cathode, the filament is the cathode and emits the electrons. In an indirectly heated cathode, the filament or heater heats a separate metal cathode electrode which emits the electrons.
The cathode is usually in the shape of a Cylinder.

S4. Ans.(b)

S5. Ans.(d)
Sol. Bus topology involves a single cable to which all the nodes of network devices are connected. It transmits the data from one end to another in single direction. So, whenever a node tries to send a message or data to other nodes, this data passes through all other nodes in the network through the cable. Hence, data is not secure.

S6. Ans.(c)
Sol. Circuit can be rearranged as,

Current flowing through 8Ω resistor is
I_1=48/(12+8)=48/20=2.4A

S7. Ans.(a)
Sol. The advantage of serial data transfer compared to parallel data transfer is that it requires lesser number of wires for transferring of data.

S8. Ans(b)
Sol. Pre-emphasis is the process of artificial boosting of high frequency components of m(t) to increase corresponding Signal to Noise ratio(S/N). It is used in the transmitter section before modulation using Lead Compensator. It is like High pass Filter or differentiator. It passes high frequency but with amplification. So, Pre-emphasis circuit is used before demodulation.

S9. Ans.(d)

S10. Ans.(a)
Sol.
File Transfer Protocol (FTP) is not a web browser. It is a standard network protocol used for the transfer of computer files between a client and server on a computer network i.e., from one host to another host over a TCP/IP based network such as the Internet.
Hyper Text Transfer Protocol (HTTP) is a “client-server” protocol used in web communications for transferring files like text, graphic image, sound, video and other multimedia files etc. on the world wide web. This is the protocol over which data is sent between our browser and the website that we are connected to. The ‘S’ at the end of HTTPS tells about the secure and encrypted communications between our browser and the website. HTTP is an application protocol that runs on the top of TCP/IP suite of protocols. The HTTP runs at 8080 i.e. 80 port address. HTTP is used as a server-client mode.
SMTP(Simple Mail Transfer Protocol) is used for sending emails (electronic mail) across IP networks.

Quiz Electronics Engineering 29 Sep 2020

Quiz Electronics Engineering
Exam: NIC
Topic: Miscellaneous
Date: 29/09/2020

Each Question carries 1 Mark
Negative Marking: 1/4
Time: 10 Minutes

Q1. Which of the following statements about electric field lines associated with electric charge is false?
(a) Electric field lines can be either straight or curved.
(b) Electric field lines form closed loops.
(c) Electric field lines begin on positive charges and end on negative charges.
(d) Electric field lines do not intersect.

Q2. For a message signal m(t) = cos(2πfmt) and carrier of frequency fc, which of the following represents a SSB signal?
(a) cos(2πfmt) cos(2πfct)
(b) cos(2πfct)
(c) [1 + cos(2πfmt) cos(2πfct)]
(d) cos[2π(fc + fm)t]

Q3. Electronic mail uses which Application layer protocol?
(a) SMTP
(b) HTTP
(c) FTP
(d) SIP

Q4. A circuit component that opposes the change in circuit voltage is
(a) Resistance
(b) Inductance
(c) Capacitance
(d) All the above

Q5. The abbreviation TTL stands for
(a) Transistor-transformer logic
(b) Transistor-transistor logic
(c) Transmitter transistor load
(d) Tuned transistor loop

Q6. 8085 has ___ software restarts and ___ hardware restarts.
(a) 10, 5
(b) 6, 6
(c) 7, 5
(d) 8, 4

Q7. A transistor is said to be in quiescent state when
(a) no signal is applied to the input
(b) no currents are flowing
(c) it is unbiased
(d) emitter junction and collector-junction biases are equal

Q8. The Fourier transform of u(t) is
(a) 1/jω
(b) jω
(c) π𝛿(ω) + 1/jω
(d) 1/(1+jω)

Q9. Which of the following expressions is true for apparent power in an A.C. circuit?
(a) VI cos ∅
(b) V_(r.m.s.) ×I_(r.m.s.)
(c) V_av.×I_av.
(d) V_peak×I_peak

Q10. For electromagnetic wave propagation in free space , the free space is defined as
(a) σ = 0, ε = 1, µ ≠ 1, p ⃗ ≠ 0, j ⃗ = 0
(b) σ = 0, ε = 1, µ = 1, p ⃗ = 0, j ⃗ = 0
(c) σ ≠ 0, ε > 1, µ < 1, p ⃗ ≠ 0, j ⃗ = 0
(d) σ = 0, ε = 1, µ = 1, p ⃗ ≠ 0, j ⃗ ≠ 0

SOLUTIONS

S1. Ans.(b)
Sol. Electric Field lines never form closed loop. Either they converge at the negative charge or direct towards infinity.

S2. Ans.(d)
Sol. In case of SSB-SC signal, either there is USB or LSB. Both cannot be present simultaneously.
Here, cos[2π(fc + fm)t] represents the Upper Side Band of either AM or SSB-SC signal.

S3. Ans.(a)
Sol. Email uses various protocols like SMTP, IMAP and POP. The most prominent one used in application layer is Simple Mail Transfer Protocol (SMTP).

S4. Ans.(c)

S5. Ans.(b)
Sol. TTL stands for Transistor-Transistor Logic. TTL is a logic family built from Bipolar Junction Transistors. TTL circuit design offered higher speed or lower power dissipation to allow design optimization. It employs a transistor with multiple emitters having more than one input.

S6. Ans.(d)
Sol. Software and Hardware Interrupts restart the operation in the 8085 microprocessor. There are 4 Hardware interrupt(TRAP, RST 5.5, RST 6.5, RST 7.5) and 8 Software Interrupts(RST_0 to RST_7). Hence, there are 4 hardware restarts and 8 software restarts.

S7. Ans.(a)
Sol. Quiescent state means “at rest”. At this state power supply is ON and stable and defined by the voltage and current present in the circuit. It shows the zero signal state of the transistors. This state describes the behavior of the transistor. The quiescent point in transistor is related to direct biasing of current to base.

S8. Ans.(c)

S9. Ans (b)
Sol. In an AC circuit, the product of the r.m.s voltage and the r.m.s current is called Apparent Power.

S10. Ans.(d)
Sol. In free space,
σ = 0,
ε = 1,
µ = 1,
Poynting vector, p ⃗ ≠ 0,
Current Density, j ⃗ ≠ 0

Quiz Electronics Engineering 28 Sep 2020

Quiz Electronics Engineering
Exam: NIC
Topic: Miscellaneous
Date: 28/09/2020

Each Question carries 1 Mark
Negative Marking: 1/4
Time: 10 Minutes

Q1. The line code that has zero dc component for pulse transmission of random binary data is
(a) non-return to zero (NRZ)
(b) return to zero (RN)
(c) alternate mark inversion (AM)
(d) none of the above

Q2. Which one of the statements is correct?
On a conducting surface boundary, electric field lines are
(a) always tangential
(b) always normal
(c) neither tangential nor normal
(d) at an angle depending on the field intensity

Q3. In a full wave rectifier circuit using centre tapped transformer, the peak voltage across half of the secondary winding is 30 V. Then PIV is:
(a) 30 V
(b) 10 V
(c) 15 V
(d) 60 V

Q4. When bundle conductor are used in place of single conductance the effective inductance and capacitance will respectively
(a) increase and decrease
(b) decrease and increase
(c) decrease and remain unaffected
(d) remain unaffected and increase

Q5. Identify the incorrect statement regarding FTP.
(a) FTP sends its control information in-band
(b) FTP uses two parallel TCP connections
(c) FTP stands for File Transfer Protocol
(d) FTP sends exactly one file over the data connection

Q6. How many bits are required to store one BCD digit?
(a) 1
(b) 2
(c) 3
(d) 4

Q7. A real signal x(f) has fourier transform X(f). Which one of the following is correct?
(a) Both magnitude and phase of X(f) have even symmetry
(b) Magnitude of X(f) has odd symmetry while phase of X(f) has even symmetry
(c) Magnitude of X(f) has even symmetry while phase of X(f) has odd symmetry
(d) Both magnitude and phase of X(f) have odd symmetry

Q8. A coil of resistance of 5 Ω and inductance 0.4 H is connected to a 50 V d.c. supply. The energy stored in the field is
(a) 20 Joules
(b) 10 Joules
(c) 40 Joules
(d) 80 Joules

Q9. The advantage of write(copy) back data cache organization is
(a) write allocate on write miss
(b) less memory bandwidth requirement
(c) Main memory consistency
(d) higher capacity

Q10. In _________ systems, resources are allocated on demand.
(a) line switching
(b) circuit switching
(c) packet switching
(d) frequency switching

SOLUTIONS

S1. Ans.(c)
Sol. There are two types coding:-
Source coding techniques are used in PCM and DM for converting analog signal to digital i.e., train of binary digits.
Line coding converts stream of binary digits into a formal code. It is used for data transmission of a digital signal over a transmission line. This process is chosen to avoid overlap and distortion of signal such as Inter-Symbol Interference.
AMI(Alternate Mark Inversion) is a synchronous clock encoding technique. It uses bipolar pulses to represent logical 1 values and a logical 0 is represented by no symbol. So, It is a three level system. This code has zero dc component for pulse transmission of random binary data.

S2. Ans.(b)
Sol. On a conducting surface boundary, the tangential component of the Electric field is zero. It is absorbed by the conducting surface. Only normal component of the Electric Field exist.

S3. Ans. (d)
Sol. In full wave circuit using centre tapped transformer PIV = 2V_m.
So, PIV = 2 × 30 = 60 V

S4. Ans.(b)
Sol. Bundled conductor are used for reducing corona loss and radio interference because it reduces voltage gradient. Hence, bundled conductors have higher capacitance and lower value of inductive reactance.

S5. Ans.(a)
Sol. FTP(File Transfer Protocol) is an application layer protocol which moves files between local and remote file systems from one system to another over the internet. It runs on the top of TCP. It uses two TCP connections i.e. data and control connections in parallel. Control Connection at port 21 and Data connection at port 20. FTP is out-of-band. Out-of-band means data that is transferred through a stream independent from the main in-band data stream.

S6. Ans(d)
Sol. BCD (Binary coded Decimal) Number is from 0 to 9, which requires four bits to store. As the maximum number of the system (15) can best represented by 4 bits. It is also called as 8421 code to represent maximum number 15.

S7. Ans.(c)

S8. Ans.(a)
Sol. Given:
R = 5 Ω
L = 0.4 H
V_dc = 50 V
Energy stored in a field is
E = 1/2 LI^2
Current in the coil is
⇒ I = V_dc/R
⇒ I = 50/5
⇒ I = 10 A
Now,
E = 1/2(0.4)〖(10)〗^2
So, E = 20 Joules

S9. Ans.(b)

S10. Ans.(c)
Sol. Packet switching is a method of transmitting data in which long messages are sub-divided into packets. In this resources are not reserved but are allocated on demand. It follows first-come first serve principle for data.