Quiz: Electrical Engineering 26 Nov 2020

Quiz: Electrical Engineering
Exam: UPPCS AE
Topic: Miscellaneous

Each question carries 1 mark.
Negative marking: 1/3 mark
Time: 10 Minute

Q1. The slip ring of wound rotor machine is made from
(a) Mild steel
(b) electrolytic copper
(c) cast iron
(d) brass
L1Difficulty 3
QTags Machine
QCreator Balwant Kumar

Q2. Which type of the following will result in a symmetrical fault?
(a) All the three phases to earth
(b) phase to line
(c) single phase to earth
(d) two phases to earth
L1Difficulty 3
QTags Switchgear and protection
QCreator Balwant Kumar

Q3. The Merz price protection is suitable for?
(a) Alternator
(b) transformer
(c) Feeder
(d) Transmission line
L1Difficulty 3
QTags Switchgear and protection
QCreator Balwant Kumar

Q4. Internal fault of Transformer is detected and protected by?
(a) Directional relay
(b) Thermal relay
(c) Buchholz relay
(d) Distance relay
L1Difficulty 3
QTags Switchgear and protection
QCreator Balwant Kumar

Q5. The most common type of fault is
(a) Single phase to ground
(b)Two phase to ground
(c) Phase to phase
(d) three phases to ground
L1Difficulty 3
QTags Switchgear and protection
QCreator Balwant Kumar

Q6. The per unit value of a 60 Ω resistance at 1000 MVA base and 100 kV base voltage is
(a) 4 pu
(b)8 pu
(c)6 pu
(d)10 pu
L1Difficulty 3
QTags Switchgear and protection
QCreator Balwant Kumar

Q7. If the fault current is 2000 A for a relay with a current setting of 50 % and CT ratio of 1000:1, the PSM would be:
(a) 1.5
(b) 4
(c) 4.5
(d) 3
L1Difficulty 3
QTags Switchgear and protection
QCreator Balwant Kumar

Q8. Current limiting reactors may be
(a) oil immersed non magnetically shielded
(b) oil immersed magnetically shielded
(c) air cored air cooled
(d) any of above
L1Difficulty 3
QTags Switchgear and protection
QCreator Balwant Kumar

Q9. Which semiconductor device behaves like two SCR’s?
(a) UJT
(b) MOSFET
(c) JEET
(d) Triac
L1Difficulty 2
QTags Semiconductors & diodes
QCreator Balwant Kumar

Q10.The power factor at which single phase induction motor usually operate is
0.7 lag
0.8 lag
0.7 lead
Unity
L1Difficulty 1
QTags Single phase induction motor
QCreator Balwant Kumar

Solutions

S1. Ans.(d)
Sol. Brass

S2. Ans.(a)
Sol. All the three phases to earth fault will result in the symmetrical fault.

S3. Ans.(a)
Sol. Alternator

S4. Ans.(c)
Sol. Internal fault of Transformer is detected and protected by Buchholz Relay.

S5. Ans. (a)
Sol. The most common type of fault is Single phase to ground.

S6. Ans. (c)
Sol. Rpu = R(ohm) ×MVA/(kV)^2
= 60 ×1000/100^2 = 6 p.u.
S7. Ans. (b)
Sol. PSM=(Fault current )/(Current setting ×CT ratio×Rated secondary current)
After putting the value in the given formulae 4 is the answer.

S8. Ans. (d)
Sol. Any of above

S9. Ans (d)
sol. Triac

S10. Ans (a)
single phase induction motor usually operate is 0.7 lag.

Quiz: Electrical Engineering 24 Nov 2020

Quiz: Electrical Engineering
Exam: UPPSC AE
Topic: Miscellaneous

Each question carries 1 mark.
Negative marking: 1/3 mark
Time: 10 Minute

Q1. A 4 A source has a shunt internal resistance of 65 Ω. The maximum power that can be delivered to a load is
(a) 270 W
(b) 460 W
(c) 260 W
(d) None of above

Q2. Which of the following represents the characteristics of Fuse wire?
(a) high R and low MP
(b) high R and high MP
(c) low R and low MP
(d) low R and high MP

Q3. Two electric bulbs whose resistances are in the ratio 2:1 is connected in parallel to a constant voltage source. The powers dissipated by them are in the ratio
(a) 1 : 2
(b) 1 : 1
(c) 2 : 1
(d) 4 : 1

Q4. The current in a 242 W, 220 V heater operated at 200 V is
(a) 50/7 A
(b) 6/5 A
(c) 1 A
(d) 55/9 A

Q5. The Electric stress in underground cable is
(a) Maximum at the conductor and minimum at the sheath
(b) Zero at the conductor as well as at the sheath
(c) Minimum at the conductor and maximum at the sheath
(d) None of the above

Q6. The voltage at farthest load point from supply at one end will be the least always for
(a) Interconnected system
(b) Radial system
(c) Ring system
(d) None of the above

Q7. What is the maximum safe current flow in a 42 Ω, 7 W resistor?
(a) 0.480 A
(b) 0.309 A
(c) 0.408 A
(d) 0.908 A

Q8. Capacitor is used in a 1 phase ac motor for
a) Providing starting Torque
b) Improvement if pf
c) Both (a) and (b)
d) None of the above

 

 

Q9. The Most suitable circuit breaker for interrupting short line fault without resistance switching is
a) Bulk oil circuit Breaker
b) SF6 Circuit breaker
c) Air Blast circuit breaker
d) None of the above

Q10. Voltmeter calibration is done through
a) a single generator
b) a potentiometer
c) an ampere hour meter
d) a hertz meter

Solution
S1. Ans.(c)
Sol. Source is connected across shunt resistance i.e. Norton’s equivalent circuit so
Here, I_N = 4 A and R_N = 65 Ω. For maximum power in the load, R_L=R_N = 65 Ω.
Therefore, current through load = I_N/2 = 4/2 = 2 A
∴ P_max = (2)² × R_L = (2)² × 65 = 260 W

S2. Ans.(a)
Sol. Fuse wire should have High R and Low MP

S3. Ans.(a)
Sol. Power dissipation = P_1/P_2 =((E^2/R_1 )/E^2 )/R_2 = R_2/R_1

S4. Ans.(c)
Sol. Resistance, R = V^2/P=(220)^2/242 = 200 Ω
∴Current,I=(Applied voltage)/R=200/200=1A

S5. Ans.(a)
Sol. The Electric stress in underground cable is maximum at the conductor and minimum at the sheath.
E_Max=V/(r ln⁡〖R/r〗 ) V/cm

S6. Ans.(b)
Sol. The voltage at farthest load point from supply at one end will be the least always for Radial System.

S7. Ans.(c)
Sol. P = I²R or I = √(P/R)=√(7/42) = 0.408A

S8. Ans(c)
Sol. Capacitor is used in a 1 phase ac motor for both of the mentioned reason.

S9. Ans(b)
Sol. SF6 Circuit breaker

S10. Ans(b)
Sol. A Potentiometer

Quiz: Electrical Engineering 21 Nov 2020

Quiz: Electrical Engineering
Exam: UPPSC AE
Topic: Miscellaneous

Each question carries 1 mark.
Negative marking: 1/4 mark
Time: 10 Minute

1.Nortan’s Theorem application in the circuit will results in __________
a) A voltage source alone
b) A current source alone
c) A current source with impedance in parallel
d) A voltage Source with current source in parallel

2. Potential terminals can be said to have a __________
a) high current capacity
b) low current capacity
c) low Voltage capacity
d) high voltage capacity

3. In a long transmission line with R, L, G & C are the resistance inductance shunt conductance and capacitance per unit length, respectively. The condition for distortion less transmission is
a) RC=LG
b) RC=√(L/C)
c) G=√(C/L)
d) RG=LC

4. In a control system, the response is critically damped if:
a) Damping factor is 0
b) Damping factor is < 1
c) Damping factor is > 1
d) Damping factor is 1

5. In order to obtain improved steady state and transient response, the following compensator may be used
a) Lead- Lag compensator
b) Lag compensator
c) Lead- Lead compensator
d) Lag- Lag compensator

6.Choose the incorrect statement amongst the given statements
a) Magnetic Flux usually flows through a minimum reluctance path
b) Field winding produces the working flux
c) Working EMF induced by working flux in armature winding
d) Commutator serve as mechanical inverter for DC generator

7. The type of dc generator used to electric arc welding is
a) Differential Compound
b) shunt
c) Series
d) Separately Excited

8. The two type of indoor type current type transformer are
a) Bushing type and clamp on type
b) Wound type and clamp on type
c) Wound type and Bar type
d) Bar type and Bushing type

9.Resistance of pressure coil in a low power factor dynamometer type wattmeter is
a) once time
b) three times
c) hundred times
d) ten times

10.Autotransformer is used in the transmission and distribution systems
a) When galvanic isolation is needed
b) When operator is not available
c) When efficiency of transformer is not critical
d) When transformation ratio for voltage is small

Solution

Sol.1 Ans (c)
A current source with impedance in parallel.

Sol.2 Ans (b)
A shunt is normally a very low value of resistance, connected in parallel with the ammeter coil. In a shunt, the potential terminals have a low current carrying capacity. As a result, a low range ammeter is used to measure the large current.

Sol.3 Ans (a)
RC=LG, For distortion less line.

Sol.4 Ans (d)

Response Damping Factor
Undamped 0
Under damped <1
Critical damped 1
Over Damped >1

Sol.5 Ans (a)
By the use of Lead- Lag compensator the desired output results can be obtained with improvement in steady state as well as transient response of the system.

Sol.6 Ans (d)
Commutator serve as mechanical inverter for DC Motor.

Sol.7 Ans (a)
The Differential Compound type of dc generator used to electric arc welding.

Sol.8 Ans (c)
Wound type and Bar type are used as indoor transformer due to low voltage rating.

Sol.9 Ans (d)
In a low power factor dynamometer type wattmeter, pressure coil has a resistance value that is one tenth of the actual with respect to unity power wattmeter. This is done in order to ensure a reasonable amount of torque at low power factors.

Sol.10 Ans (d)
When transformation ratio for voltage is small.

Quiz Electronics Engineering 19 Nov 2020

Quiz Electronics Engineering
Exam: NIC
Topic: Miscellaneous
Date: 19/11/2020

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

Q1. A series R-L-C circuit will have unity power factor if operated at a frequency of
(a) 1/(2π√LC)
(b) LC
(c) 1/(LC)
(d) 1/√LC

Q2. A device with input x(t) and output y(t) is characterized by: y(t) = x2(t). An FM signal with frequency deviation of 90 kHz and modulating signal bandwidth of 5 kHz is applied to this device. The bandwidth of the output signal is
(a) 380 kHz
(b)190 kHz
(c) 370 kHz
(d) 95 kHz

Q3. Which machine instruction is used for comparing two operands in microprocessor?
(a) CLC
(b) CMP
(c) CMC
(d) None of the Above

Q4. The Poynting vector P ⃗ = E ⃗ × H ⃗
(a) Power/unit area
(b) Volts
(c) Power
(d) Volt/unit length

Q5. A fair coin is tossed 10 times. What is the probability that ONLY the first two tosses will yield heads?
(a) (1/2)^2
(b) (_ ^10)C_2 (1/2)^2
(c) (1/2)^10
(d) 〖(_ ^10)C_2 (1/2)〗^10

Q6. After firing an SCR, the gate pulse is removed. The current in the SCR will
(a) rise up.
(b) remain same.
(c) rise a little and then fall to zero.
(d) immediately fall to zero.

Q7. Which network topology supports bidirectional links between each possible node?
(a) Mesh topology
(b) Bus topology
(c) Ring topology
(d) Star topology

Q8. In a vacuum tube, diode current flows due to
(a) electrons only
(b) holes only
(c) positive ions only
(d) none of the above

Q9. When signed numbers are used in binary arithmetic, then which of the following notations would have unique representation for zero?
(a) Sign-magnitude
(b) 1’s complement
(c) 2’s complement
(d) 9,s complement

Q10. The 1’s complement of the number 11011 is
(a) 00101
(b) 11011
(c) 10101
(d) 00100

SOLUTIONS

S1. Ans.(a)
Sol. We know that power factor is
cosϕ = R/Z
At resonance condition, Z = R
⇒ cosϕ = R/Z = 1
Hence, A series RLC circuit will have unity power factor at resonance condition only and fr =1/(2π√LC)

S2. Ans.(c)
Sol. Given:
Frequency deviation(Δf) = 90 kHz
Message signal frequency(fm) = 5 kHz
We know that,
BW = 2(Δf + fm)
As y(t) = x2(t), that means it is a doubler circuit. There will be no change in the frequency of the message signal but there will be change in Frequency deviation. It will be doubled.
Now,
BW = 2(2 x 90 + 5) = 2(180 + 5)
So, BW = 370 kHz
Therefore, The bandwidth of the output signal is 370 kHz.

S3. Ans.(b)
Sol.
CMP: compares the data byte in the register or memory with the contents of accumulator.
CMC: complement carry flag
CLC: clear carry flag

S4. Ans.(a)
Sol. We know that,
Dimension of E ⃗ = V/m
Dimension of H ⃗ = A/m
Dimension of P ⃗ = V.A/m^2 = Watt/m^2
Hence, Dimension of P ⃗ is Power/unit area.

S5. Ans.(c)
Sol. p(only first two tosses are heads) = p(H,H,T,T,T,….T)
Now, each toss is independent.
So, required probability
= p(H)× p(H)× [p(T)]^8 ….
= (1/2)^2 (1/2)^8=(1/2)^10

S6. Ans.(b)
Sol: After the SCR is turned ON, anode current goes on increasing and when becomes more than the latching current the gate loses control over the Anode current. Thus, gate pulse is removed. So, The current in the SCR will remain same.

S7. Ans.(a)
Sol. Mesh topology routes data sent through any of several possible nodes to the receiving node. It is expensive for setup as it connects every node to all nodes on the network. However, it is considered the most reliable because it is most redundant of all topology i.e. if one node fails, the network can route traffic to another node.
In a mesh topology every node is connected to every other node i.e., bidirectional links between each possible nodes. So, Total number of cable links with n nodes = n(n – 1)/2

S8. Ans.(a)
Sol. After removal of air from the tube, vacuum is created in the tube and electrons get a clear path to flow from the cathode to anode, and a current flowing from anode to cathode is created. The current starts to flow when cathode is heated and a positive voltage is applied to the anode.

S9. Ans.(c)
Sol. In 1’s complement, 9’s complement and sign-magnitude zero is represented in more than one notation but in 2’s complement it is represented in only 1 way.

S10. Ans.(d)
Sol. In Complement, we convert binary ‘1’ to ‘0’ and ‘0’ to ‘1’.
So, 1’s complement of 11011 = 00100

Quiz: Electrical Engineering 19 Nov 2020

Quiz: Electrical Engineering
Exam: UPPSC-AE
Topic: Miscellaneous

Each question carries 1 mark.
Negative marking: 1/3 mark
Time: 10 Minute

Q1. Form factor can be expressed as the ratio of
(a)Average value to rms value
(b)Rms value to average value
(c)Peak value to average value
(d)Peak value to rms value

Q2. Peak factor can be expressed as the ratio of
(a)Average value to rms value
(b)rms value to average value
(c)maximum value to average value
(d)maximum value to rms value

Q3. The transformer used for AC welding sets is
(a)Booster type
(b)Step up type
(c)Step down type
(d)Equal turn ratio type

Q4. The commutator of a DC generator acts as:
(a)Amplifier
(b)Rectifier
(c)Load
(d)Multiplier

Q5. For RLC ac series circuits at resonance the current is:
(a)Minimum at leading p.f
(b)Minimum at lagging p.f
(c)Maximum at unity p.f
(d)Maximum at leading p.f

Q6. Skin effect existence can be observed in
(a) dc as well as ac transmission line
(b) dc transmission line only
(c) ac transmission line only
(d) cable carrying dc current

Q7. Grading of cables
(a) reduce insulation cost and increase current rating.
(b) reduce insulation cost but decrease current rating.
(c) Increases both
(d) None of above

Q8. A 50 Hz 220/400 V, 50 KVA single phase Transformer operates on 220 V, 40 Hz supply with secondary winding then,
(a) the eddy current loss and hysteresis loss of transformer decreases
(b) the eddy current loss and hysteresis loss of transformer increases
(c) the hysteresis loss of transformer increases while eddy current loss remains the same
(d) the hysteresis loss remains the same whereas eddy current loss decreases

Q9. When transformer winding suffers a short circuit, the adjoining turns of the same winding experience
(a) an attractive force
(b) a repulsive force
(c) no force
(d) none of the above

Q10. Reactance relay is best suited for the protection of
(a) phase fault
(b) Earth fault
(c) open-circuit faults
(d) None of the above

Solution

S1. Ans(b)
Sol. Form factor is the ratio of Rms value to average value

S2. Ans(d)
Sol. Peak factor is the ratio of maximum value to rms value

S3. Ans(c)
Sol. Step down type

S4. Ans(b)
Sol. Rectifier

S5. Ans(c)
Sol. Maximum at unity power factor

S6. Ans. (c)

Skin effect exists in ac transmission line only.

S7. Ans.(a)
Sol. Grading of cables reduce insulation cost and increase current rating.

S8. Ans. (c)
Sol. According to the relation given, W_h∝B_m^1.6 f
W_h∝(B_m^1.6 f)/f^0.6 ∝V^1.6/f^0.6 (as V∝B_m f)
W_e∝B_m^2 f^2
S9. Ans. (a)
Sol. Due to same direction of current in the adjoining winding it experiences force of attraction.

S10. Ans. (b)
Sol. Earth faults

Quiz Electronics Engineering 17 Nov 2020

Quiz Electronics Engineering
Exam: NIC
Topic: Miscellaneous
Date: 17/11/2020

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

Q1. Which of this is not a guided media?
(a) Fiber optical cable
(b) Coaxial cable
(c) Wireless LAN
(d) Copper wire

Q2. Which of the following are electromagnetic in nature?
1. Alpha ray
2. X-ray
3. Gamma rays
4. Cathode rays
(a) 1 and 2
(b) 2 and 3
(c) 3 and 4
(d) 1cand 4

Q3. An unbiased coin is tossed an infinite number of times. The probability that the fourth head appears at the tenth toss is
(a) 0.082
(b) 0.073
(c) 0.062
(d) 0.091

Q4. The output of an Ex–NOR gate is 1. Which input combination is correct?
(a) A = 1, B = 0
(b) A = 0, B = 1
(c) A = 0, B = 0
(d) None of the above

Q5. The number of bits in a binary PCM system is increased from n to n+1. As a result, the signal quantization noise ratio will improve by a factor
(a) (𝑛+1)/𝑛
(b) 2(n+1)/n
(c) 22(n+1)/n
(d) independent of n

Q6. An instruction cycle refers to
(a) Fetching an instruction
(b) Fetching, decoding and executing an instruction
(c) Executing an instruction
(d) Clock speed

Q7. 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) 0.5𝛿(t – 0.25)
(b) 𝛿(t – 0.25)
(c) 𝛿(t – 1)
(d) 0.5𝛿(t – 1)

Q8. Piezo-electric crystal is generally employed for the measurement of which one of the following?
(a) Acceleration
(b) Velocity
(c) Flow
(d) Temperature

Q9. An operational amplifier possesses
(a) very large input resistance and very large output resistance
(b) very small input resistance and very small output resistance
(c) very large input resistance and very small output resistance
(d) very small input resistance and very large output resistance

Q10. The value of the current flowing in the 1 ohm register in the circuit shown in the given figure will be

(a) Zero
(b) 5 A
(c) 6 A
(d) 10 A

SOLUTIONS

S1. Ans.(c)
Sol. Wired medium is called guided media and wireless medium is called Unguided media. Example of guided media are Optical Fiber Cable, Coaxial Cable, Twisted Fiber Cable etc. Example of unguided media are wireless LAN.

S2. Ans.(b)
Sol. Alpha ray and cathode ray are not electromagnetic in nature.

S3. Ans.(a)
Sol. It means 3 – head appears in 1st 9 trials.
Probability of getting exactly 3 head in 1st 9 trials
= (_ ^9)C_3 ×(1/2)^3 (1/2)^6= (_ ^9)C_3 ×(1/2)^9
and in 10th trial head must appears.
So, required probability
= (_ ^9)C_3 (1/2)^9×1/2=84/1024=0.082

S4. Ans. (c)
Sol. Truth Table of Ex-NOR gate is

Therefore, The output of Ex-NOR gate is always 1 if both the inputs are same.

S5. Ans.(d)
Sol. It is given that the number of bits in a binary PCM system is increased from n to n+1.
We know that, SQNR = 3/2 2^2n
For n1 = n,
〖(SQNR)〗_1 = 3/2 2^2n
For n2 = n + 1,
〖(SQNR)〗_2 = 3/2 2^(2(n+1))
Now,
〖(SQNR)〗_2/(〖(SQNR)〗_1 ) = (3/2 2^(2(n+1)))/(3/2 2^2n ) = (3/2 2^2n.2^2)/(3/2 2^2n ) = 4
So, 〖(SQNR)〗_2 = 4〖(SQNR)〗_1
Therefore, Signal to quantization noise ratio increases by factor of 4. So this is improvement in SQNR is independent of n.

S6. Ans.(b)
Sol: An Instruction Cycle is the basic process of a computer. It is the process by which a computer retrieves a program instruction from its memory, determines what actions the instruction is asking to take and carries out those actions. It is also known as fetch decode-execute cycle.

S7. Ans.(c)
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)

S8. Ans.(a)
Sol. A piezoelectric crystal is an accelerometer that follows the piezoelectric effect of certain materials to measure dynamic changes in mechanical parameters like acceleration, vibration, and mechanical shock.

S9. Ans. (c)
Sol. In Ideal case an Op-Amp has infinite input resistance so that no current can flow across both terminals and zero output resistance so that there is no loss of signal. Hence, A practical Op-Amp has high input impedance and low output resistance.

S10. Ans.(b);
Sol. According to Superposition theorem,
CASE I: Only voltage source is present

⇒ I_1=5/1 = 5 Amp . . . . . . . . . . . . . . . . . . . . . . . . . (1)
CASE II: Only current source is present

⇒ I_2 = 0 . . . . . . . . . . . . . . . . . . . . . . . . . (2)
All 5 A current flow through the short circuit branch.
Adding 1 and 2, we get
⇒ I = I_1+I_2
So, I = 5 + 0 = 5A

Quiz Electronics Engineering 7 Nov 2020

Quiz Electronics Engineering
Exam: NIC
Topic: Miscellaneous
Date: 07/11/2020

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

Q1. Program Counter register stores the:
(a) address of the first memory block
(b) address of the next instruction to be executed
(c) address of the last memory block
(d) size of the primary memory

Q2. In class-A amplifier utilizing a direct coupled load (resistive), the maximum conversion efficiency is
(a) 25%
(b) 90%
(c) 50%
(d) none of these

Q3. Let f(x) be the continuous probability density function of a random variable X. The probability that a < X ≤ b, is
(a) f(b-a)
(b) f(b) – f(a)
(c) ∫_a^b▒〖f(x)dx〗
(d) ∫_a^b▒〖xf(x)dx〗

Q4. Which of the following diodes is limited to the reverse-bias region in its region of operation?
(a) Schottky
(b) Photodiode
(c) Tunnel
(d) Rectifier

Q5. Media of communication between operation and operated unit is not:
(a) OFC
(b) Signaling copper cable
(c) Quad copper cable
(d) Power Aluminium cable

Q6. Which layer is used to link the network support layers and user support layers?
(a) session layer
(b) transport layer
(c) data link layer
(d) network layer

Q7. Which one of the following is the impulse response of the system whose step response is given as c(t) = 0.5(1 – e^(-2t))u(t)?
(a) e^(-2t)u(t)
(b) 0.5 𝛿(t) + e^(-2t)u(t)
(c) 0.5 𝛿(t) – 0.5e^(-2t)u(t)
(d) 0.5 e^(-2t)u(t)

Q8. If P, Q and R are Boolean variables, then (P + Q’)(PQ’ + PR)(P’R’ + Q’) simplifies
(a) PQ’ + R
(b) PR’
(c) PQ’
(d) PR” + Q

Q9. The advantage of using a freewheeling diode with bridge type AC to DC converter is
(a) reliable speed control
(b) reduced cost of system
(c) regenerative braking
(d) improved input power factor

Q10. When electromagnetic waves are propagated in a waveguide
(a) They travel along the walls of the waveguide
(b) They are reflected from the walls but do not travel along the walls
(c) They travel through the dielectric without touching the walls
(d) None of the above

SOLUTIONS

S1. Ans.(b)
Sol. Program Counter is a 16-bit “Auto increment register” in which address of the next instruction to be executed is stored after the content of the current location is sent for fetch.

S2. Ans.(a)
Sol. Conversion efficiency of Class-A amplifier is
% η = (1-V_min/V_CC ) × 25%
Therefore, the maximum conversion efficiency is 25%.

S3. Ans.(c)
Sol. If f(x) is the continuous Probability Density Function of a random variable X then,
p(a < x ≤ b) = p(a ≤ x < b) = p(a ≤ x ≤ b)= ∫_a^b▒f(x)dx

S4. Ans.(b)
Sol. A Photodiode is a PN-junction diode that consumes light energy to produce electric current or voltage based on the mode of operation of the device. It is also known as photo-detector, a light detector, and photo-sensor. They mainly work in reverse bias condition. Photodiodes are used in compact disc players, smoke detectors, medical devices and the receivers for infrared remote control devices for television and AC.

S5. Ans.(d)
Sol. Except Power Aluminium cable, all others are used as communication medium between operation and operated unit.

S6. Ans.(b)
Sol. Physical, Data link and Network layers are network support layers and Session, Presentation and Application layers are user support layers. The transport layer links these layers by segmenting and rearranging the data. Protocols like TCP and UDP are used.

S7. Ans.(a)
Sol. Given:
c(t) = 0.5(1 – e^(-2t))u(t)
Impulse response is –
⇒ 𝛿(t) = (dc(t))/dt
⇒ 𝛿(t) = d/dt{0.5(1 – e^(-2t))u(t)}
⇒ 𝛿(t) =0.5(2e^(-2t))u(t)
So, 𝛿(t) = e^(-2t)u(t)

S8. Ans.(c)
Sol. (P + Q’)(PQ’ + PR)(P’R’ + Q’) = (P + Q`)P(Q` + R)(P`R` + Q`)
= (P + Q`)P(P`Q`R` + Q`Q` + P`R`R + RQ`)
= (P + Q`)P (P`Q`R` + Q` + 0 + RQ`)
= (P + Q`)(PP`Q`R` + PQ` + PRQ`) = (P + Q`)( 0 + PQ` + PRQ`)
= (P + Q`)(PQ` + PRQ’) = (P + Q`)PQ`(1 + R)
= (P + Q`)(PQ’) = PPQ` + PQ`Q`
= PQ` + PQ` = PQ’

S9. Ans.(d)
Sol: At the same firing angle, Freewheeling diode delivers more power to load as compared to without it. Volt-Ampere input is same in both the case. So, we can say that input power factor is improved due to the use of freewheeling diode.

S10. Ans.(b)
Sol. The waveguides are made up of conductor and conductor prevent travelling of waves tangential or parallel to it. Hence, the electromagnetic waves are reflected from the walls but do not travel along the walls.

Quiz Electronics Engineering 6 Nov 2020

Quiz Electronics Engineering
Exam: NIC
Topic: Miscellaneous
Date: 06/11/2020

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

Q1. Which one of the following statements is NOT true?
(a) The measure of skewness is dependent upon the amount of dispersion
(b) In a symmetric distribution, the value of mean, mode and median are the same
(c) In a positively skewed distribution: mean > median > mode
(d) In a negatively skewed distribution: mode > mean > median

Q2. _______ allows you to connect and login to a remote computer
(a) FTP
(b) Telnet
(c) HTTP
(d) SMTP

Q3. Find the voltage V_x in the given circuit.

(a) 10
(b) 20
(c) 30
(d) 40

Q4. The use of the cache in computer system increases the –
(a) available memory space for the program
(b) available memory space for the data
(c) available speed of memory access
(d) addressing range of CPU

Q5. The phase correcting circuit is:
(a) All–pass filter
(b) Low–pass filter
(c) High–pass filter
(d) Band–pass filter

Q6. Which of the following are not a unidirectional current devices?
1. BJT 2. TRIAC
3. MOSFET 4. GTO
5. IGBT
(a) 4 and 5
(b) 2 and 4
(c) 5 only
(d) 2 only

Q7. When the temperature of a doped semiconductor is increased, its conductivity
(a) Decreases
(b) Increases
(c) Does not change
(d) Increases or decreases depending on whether it is p-type or n-type

Q8. An unused input to a TTL NAND gate acts like
(a) a low level
(b) a tri-state input
(c) a high level
(d) an open circuit

Q9. Medium wave broadcast is used for
(a) international broadcast
(b) national broadcast
(c) regional broadcast
(d) none of the above

Q10. In a uniform plane wave, the value of |E|/|H| is
(a) √(µ_ /ε_ )
(b) √(ε_ /µ_ )
(c) 1
(d) µε

SOLUTIONS

S1. Ans.(d)
Sol. Options a, b, c are true but (d) is not true since in a negatively skewed distribution, mode > median > mean.

S2. Ans.(b)
Sol. Telnet is an application protocol used on the Internet or local area network to provide a bidirectional interactive text-oriented communication facility using a virtual terminal connection. It enables a user to manage an account or device remotely.

S3. Ans.(a)
Sol. Applying Kirchhoff’s Voltage law in the given circuit, we get
50 = 15 + 10+ 15 + Vx
⇒ V_x + 40 = 50
So, V_x = 10 volts

S4. Ans.(c)
Sol. The cache memory is more faster than the main or primary memory. Cache memory is a high speed semiconductor memory with very less access time as compared to main memory.

S5. Ans.(a)
Sol. All Pass Circuit passes all frequencies which are present in the input without attenuation but provides different phase shift to each frequencies. It is also called “Phase Corrector or delay Equalizer”.

S6. Ans.(d)
Sol: BJT, MOSFET, GTO(Gate Turn Off) and IGBT all are unidirectional devices. But TRIAC is a bidirectional device.

S7. Ans.(b)
Sol. As temperature increases the mobility of charge carriers decreases and this will decrease the conductivity by smaller values but at the same time there is increase in number of covalent bond broken due to increase in temperature. A large number of holes and electrons are created in equal number and this will increase the conductivity by greater margin. Hence, there is increase in net conductivity of semiconductor.

S8. Ans.(c)
Sol. An unused or disconnected input in a TTL gate acts as HIGH level because an open input results in a reverse biased emitter junction of the input transistor, just as a high level does .

S9. Ans.(c)
Sol. Medium wave broadcast is used for regional broadcast.

S10. Ans.(a)
Sol. In a uniform plane wave,
σ = 0
η = (|E|)/(|H|) = √(µ/ε)
where,
η is Intrinsic Impedance.

Quiz Electronics Engineering 3 Nov 2020

Quiz Electronics Engineering
Exam: NIC
Topic: Miscellaneous
Date: 03/11/2020

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

Q1. Let P(E) denote the probability of the event E. Given P(A) = 1, P(B) = 1/2 the values of P(A/B) and P(B/A) respectively are
(a) 1 , 1/2
(b) 1/2, 1/4
(c) 1/2 , 1
(d) 1/4, 1/2

Q2. Introduction of +ve feedback in an amplifier
(a) increases the voltage gain
(b) initiates oscillations to occur
(c) is not possible
(d) decreases the voltage gain

Q3. In a network made up of linear resistors and ideal voltage sources, values of all resistors are doubled. Then the voltage across each resistor is.
(a) Doubled
(b) Halved
(c) Not changed
(d) Decreased four times

Q4. Evaluate (X ⊕ Y) ⊕ Y
(a) All 1’s
(b) All O’s
(c) Y
(d) X

Q5. The point form of the relation connecting vector magnetic potential A ⃗ and current density J ⃗ is
(a) ∇^2 A ⃗ = -µ_o J ⃗
(b) A ⃗ = ∫▒(µ_o J ⃗)/4πεRdv
(c) ∇ × A ⃗ = J ⃗ + (∂D ⃗)/∂t
(d) (∂A ⃗)/∂t = -J ⃗/σ

Q6. If a continuous time signal x(t) can take on any value in the continuous interval(-∞, ∞), it is called
(a) Deterministic signal
(b) analog signal
(c) random signal
(d) digital signal

Q7. In order to prevent overloading of the last IF amplifier in a receiver, one should use
(a) Squelch
(b) Double conversion
(c) Variable sensitivity
(d) Variable selectivity

Q8. An intrinsic semiconductor at absolute zero temperature
(a) has a large number of holes.
(b) behaves like an insulator.
(c) behaves like a metallic conductor.
(d) has few holes and same number of electrons.

Q9. What is the length of SP(Stack Pointer)?
(a) 16 bits
(b) 12 bits
(c) 8 bits
(d) 6 bits

Q10. Three or more devices share a link in _________ connection.
(a) Unipoint
(b) Polar point
(c) Point to point
(d) Multipoint

SOLUTIONS
S1. Ans.(a)
Sol. Given:
P (A) = 1
P (B) =1/2
Both events are independent
⇒ P(A∩B) = 1/2
Now,
P(A\B) = P(A∩B)/P(B)
∴ P(A\B) = (1/2)/(1/2)=1
and P(B\A) = P(A∩B)/P(A)
∴ P(B\A) = (1/2)/1= 1/2

S2. Ans.(b)
Sol. The positive feedback increases the gain of the amplifier. It has the disadvantages of increased distortion and instability. So, It is not used in amplifier. It is used in oscillators. If positive feedback is sufficient large, it leads to oscillations.

S3. Ans.(c)
Sol. If value of resistors changes then current flowing through it also changes because high resistance decreases flow of current and low resistance allow more current to flow through it. Hence, Voltage remains constant.

S4. Ans.(d)
Sol.
(X ⊕ Y) ⊕ Y = [X`Y+XY`]⊕ Y [Applying XOR operation]
= [X`Y+XY`]Y` + [X`Y+XY`]`Y
= [X`Y+XY`]Y` + [XY+X`Y`]Y [XOR + Inverter = XNOR]
= X`YY` + XY`Y` + XYY + X`Y`Y
= 0 + XY` + XY + 0 [YY`=Y; Y`Y`=Y`; YY=Y; Y`Y=0 ]
= X(Y+Y`) = X

S5. Ans.(a)

S6. Ans.(b)

S7. Ans.(c)
Sol. In order to prevent overloading of the last IF amplifier in a receiver, one should use Variable sensitivity.

S8. Ans. (b)
Sol. An intrinsic semiconductor at absolute zero temperature behaves as an Insulator because no charge carriers flow at T = 0K. All electrons lie in the VB and they don’t have sufficient energy to jump to conduction band.

S9. Ans.(a)
Sol. Stack Pointer is a part of Stack register. It is used to store data or address during the execution of sub program so that processor can easily return to main program after the execution of the sub program. The physical address for read and write in stack is obtained by adding content of stack pointer with the base address of stack segment.

S10. Ans.(d)

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: Electrical Engineering 26 Oct 2020

Quiz: Electrical Engineering
Exam: SSC JE
Topic: Miscellaneous

Each question carries 1 mark.
Negative marking: 1/4 mark
Time: 10 Minute

Q1. For V-curve for a synchronous motor the graph is drawn between
(a) Armature current and power factor
(b) Field current and armature current
(c) Terminal voltage and power factor
(d) Power factor and field current

Q2. The repulsion-start induction-run motor is used because of:
(a) High starting torque
(b) Good power factor
(c) High efficiency
(d) Minimum cost

Q3. The ratio of puncture voltage to the flashover voltage of an insulator is
(a) Equal to one
(b) Lower than one
(c) Zero
(d) Greater than one

Q4. The resistance welding process requires a
(a) High value of ac current at low voltage
(b) Low value of ac current at high voltage
(c) High value of dc current at low voltage
(d) Low value of dc current at high voltage

Q5. In arc welding, the electrodes are made of
(a) Copper
(b) Aluminum
(c) Graphite
(d) ACSR conductor

Q6. Earth fault relays are
(a) Directional relays
(b) Non-directional relays
(c) Short operate time relays
(d) Long operate time relays

Q7. In which of the single-phase motor the rotor has no teeth or winding?
(a) Universal motor
(b) Split phase Motor
(c) Reluctance Motor
(d) Hysteresis motor

Q8. In a capacitor start single phase induction motor, the current in the
(a) Supply lines leads the voltage
(b) Starting winding lags the voltage
(c) Main winding leads the voltage
(d) Starting winding leads the voltage

Q9. Which of the following welding process uses non-consumable electrode?
(a) LASER welding
(b) MIG welding
(c) TIG welding
(d) Ion-beam welding

Q10. A 220 V DC machine has an armature resistance 1 Ω. If the full load current is 20 A, the difference of induced voltage between generator and motor is
(a) 0 V
(b) 20 V
(c) 40 V
(d) 60 V

SOLUTIONS
S1. Ans.(b)
Sol. V curve is a plot of the stator current versus field current for different constant loads.

S2. Ans.(a)
Sol. The repulsion-start induction-run motor is used because of high starting torque.
The starting torque of the repulsion start motor is 350 percent with moderate starting current.
It is usually applicable where the starting period is of a long duration because of high inertia of the load. such as the high-speed lift.

S3. Ans.(d)
Sol. Flashover Voltage: The voltage at which the air around insulator breaks down and flashover takes place shorting the insulator is called Flash Over Voltage.
Puncture Voltage: The voltage at which the insulator breaks down and current flows through the inside of insulator is called Puncture Voltage.
As puncture destroys the insulator, it is more serious than flash-over. Therefore, Safety Factor is defined for an Insulator. Safety factor of an Insulator is defined as the ration of Puncture Voltage to the Flash Over Voltage.
Safety Factor = Puncture Voltage / Flash Over Voltage
So, (Puncture Voltage)/(Flash Over Voltage)>1
For pin type insulator the value of Safety Factor is about 10 which mean that Puncture Voltage is 10 times that of Flash Over Voltage.

S4. Ans.(a)
Sol. In welding process step down transformer is used which has low voltage and high current.

S5. Ans.(c)
Sol. In arc welding, the electrodes are made of graphite.

S6. Ans.(b)
Sol. if the fault current passes in either direction in earth fault relay, it gives a trip condition. Hence, earth fault relay is a non-directional relay.

S7. Ans.(d)
Sol. Hysteresis motor doesn’t have teeth or winding; therefore, these motors are free from mechanical vibration.

S8. Ans.(d)
Sol. In the capacitor start inductor motor two winding is used, the main winding and the starting winding. With starting winding, we connect a capacitor so the current flowing in the capacitor leads the applied voltage by some angle 𝟇.

S9. Ans.(c)
Sol. In TIG welding process uses non-consumable TUGSTEN electrode is used.

S10. Ans.(c)
Sol. in case of generator: E_g=V_t+I_a R_a
In case of motor: E_b=V_t-I_a R_a
∴E_g-E_b=2I_a R_a=2×20×1=40 V

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.