Quiz: Civil Engineering 31 Oct 2020

Quiz: Civil Engineering
Exam: SSC-JE
Topic: Miscellaneous

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

Q1. While estimating for plastering, usually no deduction is made for –
(a) Ends of beams
(b) Small opening upto 0.5 sq. m.
(c) End of rafters
(d) All the above

Q2. The process of applying cement mortar under pressure through a nozzle is called:
(a) Pressurizing
(b) Prestressing
(c) Guniting
(d)Screeding

Q3. The factor of safety for steel as compared to concrete is ……………
(a) Higher
(b) Same
(c) Lower
(d) None of these

Q4. Generally, strength of concrete is considered negligible/ very low in
(a) Compression
(b) Tension
(c) Fatigue
(d) None of the above

Q5. A fully saturated soil has a water content of 200 percent. If G = 2.6, the void ratio is:
(a) 1.3
(b) 2.6
(c) 5.2
(d) None of these above

Q6. A fluid in which resistance to deformation is independent of the shear stress, is called ___________.
(a) Bingham plastic fluid
(b) Pseudo plastic fluid
(c) dilatant fluid
(d) Newtonian fluid

Q7. A column that fails due to direct stress, is called:
(a) short column
(b) long column
(c) weak column
(d) medium column

Q8. A first class brick when immersed in cold water for 24 hours should not absorb water more than:
(a) 15 %
(b) 20%
(c) 22%
(d) 25%

Q9. The initial setting time for quick cement is
(a) 5 seconds
(b) 5 minutes
(c) 5 hours
(d) 5 days

Q10. According to IS : 456 – 2000 side-face reinforcement should be provided when depth of web of a beam exceeds.
(a) 650 mm
(b) 700 mm
(c) 725 mm
(d) 750 mm

SOLUTIONS

S1. Ans.(d)
Sol.
Plastering is measured in terms of m².If,
(a) opening area < 0.5 m² (No deduction is applied)
(b) opening area is between 0.5 m² – 3m², then (single side deduction is applied)
(c) opening area > 3 m², then (double side deduction is applied)

S2. Ans.(c)
Sol. The process of applying cement mortar under pressure through a nozzle is called Guniting . The machine which is used for guniting is called cement gun. It apply a pressure of 2.5 kg/cm² – 3.5 kg/cm² through nozzle.

S3. Ans.(c)
Sol. factor of safety of steel ⇒1.15
Factor of safety of concrete ⇒ 1.5
→ Due to variability in strength of concrete due to poor quality control, poor work man ship etc, higher factor of safety is given for concrete in comparison to steel.

S4. Ans.(c) → The strength of concrete in fatigue is negligible.
→ Strength of concrete in tension is 10 to 15% of compressive strength.

S5. Ans.(c)
Sol. water content (w) = 200%
G= 2.6
Void Ratio (e) = ?
→ soil is fully saturated (S = 1)
Se = WG
1×e = 2×2.6
▭(e=5.2)

S6. Ans.(d)
Sol. For Newtonian fluid there is constant viscosity for different fluid at particular temp which resist the deformation without any influence of shear stress. In other word dynamic viscosity is constant for particular fluid at particular temp.

S7. Ans.(a)
Sol. The short column fails primarily due to direct stress because in short column the buckling stresses are very small compared to direct stresses.

S8. Ans.(b)
Sol. A first class brick when immersed in water for 24 hours should not absorb water more than 20% While second class brick should not absorb more than 22% water when immersed in water for 24 hours.

S9. Ans.(b)
Sol. the initial setting time and final setting time for quick settling cement is 5 min. and 30 min respectively. it is produced by adding aluminium sulphate in very fine powdered form.

S10. Ans.(d)
Sol. when depth of the beam exceeded 750 mm or depth of the beam exceeded 450 mm & Torsion is also applied then side face reinforcement of 0.1% of gross area (BD) must be provided. Its spacing not more then 300 mm or width of beam.

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: Civil Engineering 30 Oct 2020

Quiz: Civil Engineering
Exam: SSC-JE
Topic: Miscellaneous

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

Q1. As per Lacey’s theory, the silt factor is
(a) Directly proportional to average particle size
(b) Inversely proportional to average particle size
(c) Directly proportional to square root of average particle size
(d) Not related to average particle size

Q2. Hollow bricks are generally used with the purpose of…………..
(a) Reducing the cost of construction
(b) Providing insulation against heat
(c) Increasing the bearing area
(d) Ornamental look

Q3. Lap length in compression shall not be less than
(a) 15 ϕ
(b) 20 ϕ
(c) 24 ϕ
(d) 30 ϕ

Q4. As per Environmental protection Act, 1986, the noise level in the industrial area during day should not be more than:
(a) 75 dB
(b) 65 dB
(c) 45 dB
(d) 55 dB

Q5. The final deflection due to all loads including the effects of temperature, creep and shrinkage and measured from as–cast level of supports of floors, roofs and all other horizontal members should not exceed …………..
(a) Span/350
(b) Span/300
(c) Span/250
(d) Span/200

Q6. The load at the free end of a uniform cantilever beam is increased, the failure will occur
(a) at the middle
(b) at the fixed end
(c) at the point of application of load
(d) any where in the span

Q7. Mullion is _________ member employed to sub divide a window or door opening vertically.
(a) Horizontal
(b) Inclined (at 45o)
(c) Vertical
(d) Inclined (at 60o)

Q8. The capillary depression in mercury is on account of
(a) adhesion being larger than the viscosity
(b) surface tension being larger than the viscosity
(c) cohesion being greater than the adhesion
(d) vapour pressure being small

Q9. The viscosity of a gas
(a) decreases with increase in temperature
(b) increases with increases in temperature
(c) is independent of temperature
(d) is independent of pressure for very high pressure intensities

Q10. The ruling gradient for plain and rolling terrain is
(a) 3.3%
(b) 5%
(c) 6%
(d) 4 %

SOLUTIONS

S1. Ans.(c)
Sol. As per Lacey’s theory, the silt factor is directly proportional to square root of average particle size.
As per Lacey’s the silt factor (f)= 1.76 √dmm

S2. Ans.(b)
Sol. Hollow bricks are generally used to reduce the transmission of heat, sound and dampness.

S3. Ans.(c)
Sol. → (Lap length in flexure tension)/(Ld (or)30ϕ)_greater
→ (Lap length in Direct tension)/(2Ld (or)30ϕ)_greater
→ (Lap length in compression)/(Ld (or)24ϕ)_greater

S4. Ans.(a)
Sol. as per environmental protection ACT, 1986, the noise level for different zones are following –
Zone                                   Day                   Night
Industrial                            75dB                70dB

Commercial                        65dB                 55dB

Residential                          55dB                 45dB

Silence                                50dB                  40dB

S5. Ans.(c)
Sol. deflection after partition (final deflection) = Span/250
Deflection before partition = Span/350

S6. Ans.(b)
Sol. If the load at the free end of a cantilever beam is increased the failure will occur at the fixed end because due to increase of load moment resisted by fixed support is increased and when support moment reaction increased beyond its limit then failure occur.

S7. Ans.(c)
Sol. Mullion is a vertical member. It is often provided to give aesthetic appearance. It is also provided to extend extra support to structure which has large opening.

S8. Ans.(c)
Sol. the capillary depression in mercury is one account of cohesion being greater than the adhesion. The liquid will not wet the solid surface in this phenomenon and the liquid surface is concave downward with the angle of contact greater than 90° and less than 180°.

S9. Ans.(b)
Sol. As we know that
⇒ With increasing temp. viscosity of liquid decrease because as we increase the temperature which cause decreases the cohesive forces between modulus so that viscosity is decrease
⇒ with increasing temp. viscosity of gas increases because as we increase the temp. which cause increase the rate of molecules momentum transfer which is the main reason of viscous forces within the gases. So that viscosity in increase.

S10. Ans.(a)
Sol. The ruling gradient for plain and rolling terrain is 3.3% or 1 in 30 while for mountainous terrain it is 5% or 1 in 20.

Quiz: Electrical Engineering 29 Oct 2020

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

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

Q1. The relative permeability of a medium is equal to (with M=magnetization of medium and H=magnetic field strength)
(a) 1+M/H
(b) 1-M/H
(c) 1+√(M/H)
(d) 1-√(M/H)

Q2. For the circuit given in figure below the power delivered by the 2-volt source is given by

(a) 4 W
(b) -4 W
(c) 2 W
(d) -2 W

Q3. Elements R, L and C are connected in parallel, the impedance of the parallel combination can be expressed as
Z(s)=10s/(s^2+s+400)
The value of the individual elements R, L and C are
(a) 10 Ω, 40 H and 0.1 F
(b) 10 Ω, 1/40 H and 0.1 F
(c) 4 Ω, 1 H and 0.1 F
(d) 1 Ω, 40 H and 10 F

Q4. Which of the following represents the operating region slips of a 1-phase induction motor?
(a) 0<s<2
(b) -2<s<2
(c) 0<s<1
(d) -1<s<1

Q5. If the torque/weight ratio of an instrument is low, then it can be concluded that
(a) The meter will have a uniform scale
(b) The meter will have the non-uniform scale
(c) The sensitivity of the meter will be high
(d) The sensitivity of the meter will be low

Q6. The Ybus matrix of a 100-bus interconnected system is 80% sparse. Then, the number of transmission lines in the system must be
(a) 1500
(b) 1900
(c) 3000
(d) 950

Q7. Consider the following statements in connection with frequency domain specifications of a control system:
1.Resonant peak and peak overshoot are both functions of the damping ratio ξ only.
2.The resonant frequency ω_r=ω_n for ξ > 0.707.
3.Higher the resonant peak, higher is the maximum overshoot of the step response.
Which of the statements given above are correct?
(a) 1 and 2
(b) 2 and 3
(c) 1 and 3
(d) 1, 2 and 3

Q8. An ideal transformer has an input voltage of 480V. The output current and voltage are 10A and 120V respectively. Determine the value of input current-
(a) 25 A
(b) 2.5 A
(c) 0.25 A
(d) 0.025 A

Q9. The no-load current drawn by transformer is usually what percentage of the full-load current?
(a) 0.2 to 0.5 %
(b) 12 to 15 %
(c) 20 to 30 %
(d) 2 to 5 %

Q10. The secondary winding of which of the following transformers is always kept closed?
(a) Current transformer
(b) Voltage transformer
(c) Power transformer
(d) Step-down transformer

SOLUTIONS
S1. Ans.(a)
Sol. Magnetic susceptibility(X)=M/H=µ_r-1
Where, µ_r=relative permeability
∴µ_r=1+X=1+M/H

S2. Ans.(c)
Sol.

Here, i=2/1=2 A
On applying KCL at node a: I=i-1=2-1=1 A
i.e. the current delivered by the voltage source=1 A
∴power delivered by the voltage source=2×1=2 W

S3. Ans.(b)
Sol. Given that, Z(s)=10s/(s^2+s+400)
∴Y(s)=1/Z(s) =(s^2+s+400)/10s=s/10+1/10+40/s=sC+1/R+1/SL
On comparing: C=1/10 F,R=10 Ω and L=1/40 H

S4. Ans.(a)
Sol. In a 1-phase induction motor, due to both forward and backward torque slips, the operating region lies between 0 and 2. In motoring mode slip is 0 to 1 and breaking mode 1 to 2.

S5. Ans.(d)
Sol. The low torque/weight ratio signifies heavy weight of the moving system due to which the instrument incurs frictional losses hence the sensitivity will be low.

S6. Ans.(d)
Sol. Number of buses, N=100
Sparsity, s=0.8
Then, the number of transmission lines is given as: N_T=(N^2 (1-s)-N)/2=(100^2 (1-0.8)-100)/2
⇒N_T=(100×19)/2=950

S7. Ans. (c)
Sol. → Resonant Peak (M_r) = 1/(2ξ √(1-ξ²))
Peak overshoot = e (-ξπ)/√(1-ξ²)
Resonant frequency (wr) = Wn √(1-2ξ²)
For ξ = 0
wr = Wn.

S8. Ans.(b)
Sol. V₁I₁ = V₂I₂
⇒ I₁ = (V₂I₂)/(V₁)
=(120×10)/480=2.5 A

S9. Ans.(d)
Sol. Current required to set up magnetic flux in a magnetic material is rather low. Hence no-load primary current is a very small fraction of the rated full load current

S10. Ans.(a)
Sol. Because if CT secondary is not shorted then it can develop a very high voltage across secondary which may damage transformer insulation.

Quiz: Civil Engineering 28 Oct 2020

Quiz: Civil Engineering
Exam: SSC-JE
Topic: Miscellaneous

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

Q1. A soil has plastic limit of 20% and plasticity index of 40%. If the natural water content of the soil is 34%, then the consistency index is equal to
(a) 0.35
(b) 0.65
(c) 0.82
(d) 1.00

Q2. Which of the following acts as retarder for the concrete?
(a) Calcium chloride
(b) Gypsum
(c) Calcium stearate
(d) Aluminium powder

Q3. A heterotroph is an organism that obtains
(a) its cell carbon from an inorganic source
(b) its energy from the oxidation of simple inorganic compounds
(c) its cell carbon as well as its energy from organic matter
(d) its energy from a natural ecosystem

Q4. For estimation of painted area of semi corrugated asbestos cement sheets, percentage increase in area above the plain area is _____ .
(a) 0.1
(b) 0.14
(c) 0.2
(d) 0.25

Q5. The critical depth of flow in a most economical triangular channel section for a discharge of 1 m³/sec is given by
(a) (1/9.8)^(1/5)metre
(b) (1/9.8)^(1/3)metre
(c) (1/4.9)^(1/5)metre
(d) (1/4.9)^(1/3)metre

Q6. The water utilized by the plants is available in soils mainly in the form of
(a) Chemical water
(b) Hydroscopic water
(c) Capillary water
(d) Gravity water

Q7. Axial load carrying capacity of RC column of gross area of concrete Ac, area of steel As and permissible stresses δ_c in concrete and δ_s in steel, m – modular ratio is given as:
(a) δ_c A_c+(m–1)δcAs
(b) δ_s As+mδcAs
(c) δcAs+δ_c As
(d) δ_c (Ac-As)+δcAs

Q8. If all the dimensions of a prismatic bar of square cross-section suspended freely from the ceiling of a roof are doubled then the total elongation produced by its own weight will increase.
(a) eight times
(b) four times
(c) three times
(d) two times

Q9. The purpose of stiffeners in a plate girder is to :
(a) take care of bearing stress
(b) increase the moment carrying capacity of the girder
(c) prevent buckling of web plate
(d) reduce the shear stress

Q10. When 1 cm on a map represents 10 m on the ground, the representative fraction of the scale is:
(a) 1/100
(b) 1/10000
(c) 1/1000
(d) 1/10

SOLUTIONS

S1. Ans.(b)
Sol. Given,
W_P=20%
W_n=34%
I_P=40 %
I_C= ?
I_c=(W_L-W_n)/(W_L-W_P )=(W_L-W_n)/I_P
Here,
I_P=40%
W_L-W_P=40%
W_L-20%=40%
W_L=60%
Now,
I_C=(60%-34%)/40
▭(I_C=0.65)

S2. Ans.(b)
Sol. Calcium chloride → Accelerator
Gypsum → Retarder
Calcium stearate → water proofer
Aluminium powder → Air entraining agent

S3. Ans.(c)
Sol. Autotrophs → Derive both material (cell carbon) and energy from inorganic substances.
Heterotrophs → Derive both material (cell carbon) and energy from organic substances.

S4. Ans.(a)
Sol. for estimation of painted area of semi corrugated asbestos cement sheets, percentage increases in area above plain are is 10% or 0.1 and for corrugated steel sheets, the plain area of sheets should be increased by 10% or 0.1.

S5. Ans.(c)
Sol. for most economical triangular channel section, the side slope m = tanθ = tan 45
▭(m=1)
Given, Q = 1 m³/sec.
Now, critical depth for triangular channel
Section –
y_c=((2Q^2)/(gm^2 ))^(1\/5)
=[(2×(1)^2)/(9.8×(1)^2 )]^(1\/5)
▭(y_c=(1/4.9)^(1\/5) metre)

S6. Ans.(c)
Sol. The water utilized by the plants is available in soils mainly in the form of capillary water. Capillary water is responsible for growth of plants while hydroscopic water is attached with the soil particle hence it cannot be extracted by plants.

S7. Ans.(a)
Sol. Axial load carrying capacity for RC-column is given by-
▭(P=δ_C A_C+(m-1) δ_c A_S )
Where, δ_C = Permissible stress in concrete
A_C = Gross area of concrete
δ_S = Permissible stress in steel
A_S = Area of steel
m = modular ratio

S8. Ans.(b)
Sol. Total elongation in a prismatic bar due to its self weight is given by-
▭(∆L=(yL^2)/2E)
Now, length of bar is doubles then Total elongation in bar will be-
∆L^’=(γ×(2L)^2)/2E
=4×(γL^2)/2E
▭(∆L^’=4∆L)

S9. Ans.(c)
Sol. Stiffeners are typically plate welded to the web. These plates increase the moment of inertia of plate girder which enhance the rigidity in turns it prevent buckling of web plate. To increase the moment carrying capacity of the girder, we provide the cover plates on flange.

S10. Ans.(c)
Sol. Representative fraction (RF) of the scale is
1cm → 10m.
1cm → 1000 cm.
▭(RF⇒1/1000)

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: Electrical Engineering 24 Oct 2020

Quiz: Electrical Engineering
Exam: SSC JE
Topic: Miscellaneous

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

Q1. In a synchronous machine, if the filed flux is ahead of the armature field axis, in the direction of rotation, the machine works as-
(a) asynchronous motor
(b) asynchronous generator
(c) synchronous motor
(d) synchronous generator

Q2. Synchronous motor can be made self-starting by providing
(a) Damper winding on rotor poles
(b) Damper winding on stator
(c) Damper winding on stator as well as rotor poles
(d) None of these

Q3. The coil of a moving coil meter has 100 turns, is 40 mm long and 30 mm wide. The control torque is 240×10-6 N-m on full scale. If magnetic flux density is 1Wb/m2, range of meter is
(a) 1 mA
(b) 2 mA
(c) 3 mA
(d) 4 mA

Q4. If the cathode of the thyristor is made positive with respect to the anode & no gate current is applied then: –
(a) Only the middle junction is forward biased
(b) Only the middle junction is reversed biased
(c) All the junctions are forward biased
(d) All the junctions are reversed biased

Q5. In a dynamometer type wattmeter, the pressure coil connected across the load terminal is
(a) Highly inductive
(b) Highly capacitive
(c) Highly resistive
(d) Non inductive

Q6. Due to the inductance in the pressure coil of dynamometer type wattmeter, the reading will be
(a) High for both leading and lagging power factors
(b) Low for both leading and lagging power factors
(c) High for lagging power factor and low for leading power factor
(d) Low for lagging power factor and high for leading power factor

Q7. If the number of turns of a coil is increased, its inductance
(a) Is decreased
(b) Remains the same
(c) Is increased
(d) None of the above

Q8. Mho relay is used for protection in:
(a) Long transmission lines
(b) Short transmission lines
(c) Medium transmission lines
(d) Both long transmission lines and short transmission lines

Q9. Which of the following type of instrument is used only for D.C?
(a) Moving iron-attraction type
(b) Moving iron-repulsion type
(c) Permanent magnet type
(d) Hot wire type

Q10. At a frequency less than the resonant frequency_____:
(a) series circuit is capacitive and parallel circuit is inductive
(b) series circuit is inductive and parallel circuit is capacitive
(c) both circuits are inductive
(d) both circuits are capacitive

SOLUTIONS
S1. Ans.(d)
Sol.

In and alternator, field flux is a head of armature field flux in the direction of rotation.

S2. Ans.(a)
Sol. Synchronous motor is not self-starting. It can be made self-starting by providing “Damper winding on ROTOR pole faces and around the pole shoes.
Following is the primary function of damper winding: –
(i) Provides starting torque
(ii) Reduce hunting
(iii) Used for salient pole rotors
(iv) Under normal running condition, damper winding in synchronous machine does not carry and current because the relative velocity between the rotating magnetic field (RMF) of stator and the rotor is zero.

S3. Ans.(b)
Sol. In case of moving coil meter, Controlling torque Tc = NBIA.
Where, N = no. of turns of the coil, B – magnetic flux density, = A = area of coil.
So, I = 240×10-6 / (100 × 0.04 × 0.03) = 2mA.

S4. Ans.(a)
Sol. Anode must be positive with respect to the cathode so that SCR will be forward biased. To turn on an SCR, a current is to be passed through the gate terminal. Hence it is a current operated device.

With the gate open, if the cathode is made positive with respect to the anode, the junctions J1 and J3 become reverse biased and J2 forward biased. Still the current flowing is leakage current, which can be neglected as it is very small. The SCR is said to be in reverse blocking state and voltage applied is called reverse voltage.

S5. Ans.(c)
Sol. In a dynamometer type wattmeter, the pressure coil connected across the load terminal is highly Resistive.

S6. Ans.(c)
Sol. Because of the inductance, the current of the pressure coils lags behind the voltage. Thus, the power factor of the wattmeter becomes lagging, and the meter reads high reading and vice-versa.

S7. Ans.(c)
Sol. inductance of a coil is given by: L=(N^2µA)/l
∴L α N^2
Hence, L increases if number of turns(N) increases.

S8. Ans.(a)
Sol. Relay used for different configuration of transmission lines……
Short transmission line: reactance relay
Medium transmission line: impedance relay
Long transmission line: mho relay

S9. Ans.(c)
Sol. PMMC
→ only for DC
→ Scale is uniform
→ Eddy current damping is used
→ F = BIL
→ Torque/Weight ratio is high to reduce frictional errors.

S10. Ans.(a)
Sol. For series Resonant RLC circuit

Parallel RLC circuit

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: Civil Engineering 23 Oct 2020

Quiz: Civil Engineering
Exam: SSC-JE
Topic: Fluid Mechanics

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

Q1. Capillary rise is maximum for
(a) coarse grained soils
(b) find grained soils
(c) will graded soils
(d) gap graded soils

Q2. The viscosity of a fluid with specific gravity 1.3 is measured to be 0.0034 N-sec./m². Its kinetic viscosity, in m²/s, is
(a) 2.6 × 10–6
(b) 4.4 × 10–6
(c) 5.8 × 10–6
(d) 7.2 × 10–6

Q3. Specific speed of a centrifugal pump is
(a) (N√Q)/H
(b) (N√H)/Q
(c) (N(H)^(3/4))/√Q
(d) None of these

Q4. The force of attraction between the individual particles bound together is known as
(a) Dilatancy
(b) Adhesive
(c) Cohesion
(d) Internal friction

Q5. A two-dimensional flow field is given by stream function Ψ = x² – y². The magnitude of absolute velocity at a point (1,1)
(a) 2
(b) 4
(c) 8
(d) 2√2

Q6. The centre of gravity of the volume of liquid displaced is called
(a) centre of pressure
(b) centre of buoyancy
(c) metacentre
(d) none of these

Q7. The alternate depths at a section in a rectangular channel are 0.4 m and 1.6 m respectively. The specific energy at the section is
(a) 1.68 m
(b) 1.00 m
(c) 0.64 m
(d) 0.41 m

Q8. The Chezy’s and Manning’s formulae are related by
(a) C=1/n R^(1/6)
(b) C=nR^(1/6)
(c) C=〖Rn〗^(1/6)
(d) C=1/R n^(1/6)

Q9. In two dimensional flow, the equation of a streamline is given as
(a) dy/u=dx/v
(b) dx/u=dy/v
(c) dx/dt=u,dy/dt=v
(d) u/dx=dy/v

Q10. Spherical shape of droplets of mercury is due to
(a) high density
(b) high surface tension
(c) high adhesion
(d) high cohesion

SOLUTIONS

S1. Ans.(b)
Sol. Height of capillary rise in a tube is given by
▭(h=σcosθ/(dγ_(w ) ))
▭(h∝1/d)
So, for fine grained soil effective size ‘d’ is smaller so it will experience more capillary rise.

S2. Ans.(a)
Sol. Given, Dynamic viscosity (μ)=0.0034 (N-sec)/m^2
Specific gravity (G)=1.3
We know,
G=(densityi of fluid(ρ))/(Density of water(ρω) )
1.3=ρ/1000
▭(ρ=1300 kg\/m^3 )
Kinematic viscosity (ν)=(Dynamic viscosity (μ))/Density(ρ)
=0.0034/1300
ν=2.615×10^(-6) m^2/Sec

S3. Ans.(d)
Sol. Specific speed of a centrifugal pump is given by-
▭(N_s=(N√Q)/(H_m )^(3\/4) )
Where N_s= specific speed
N= Rotating speed rpm
Q= Capacity at optimum efficiency
H_m= Total head developed at optimum efficiency point

S4. Ans.(b)
Sol. Adhesion → It is an attractive force between different kind of fluid molecules.
Cohesion → It is an attractive force between same kind of fluid molecules.

S5. Ans.(d)
Sol. given, stream function Ψ = (x²-y²)
Magnitude of absolute velocity at point (1, 1) = ?
Now,
V_x=∂Ψ/∂y
V_x= -2y
▭(〖V_x〗_((1,1) )= -2)
V_y=(-∂Ψ)/∂x
V_y= -2x
▭(〖V_y〗_1,1= -2)
V=√((V_x )^2+(V_y )^2 )
=√((-2)^2+(-2)^2 )
=√8
▭(V=2√2)

S6. Ans.(b)
Sol. When a body is partially or completely submerged in fluid then it experiences a force in vertical upward direction called as buoyancy force and the center of gravity of the volume of liquid displaced is called center of buoyance.

S7. Ans.(a)
Sol. Given, alternate depths
y_1=0.4 m.
y_2=1.6 m.
Specific energy is given by
▭(E=(y_1^2+y_1 y_2+y_2^2)/(y_1+y_2 ))
E=((0.4)^2+(0.4×1.6)+(1.6)^2)/(0.4+1.6)
=3.36/2
▭(E=1.68 m)

S8. Ans.(a)
Sol. The relation between manning’s and chezy’s coefficient are
▭(C=1/n R^(1\/6) )
C = Chezy’s coefficient
n = manning’s coefficient
R = Hydraulic radius

S9. Ans.(b)
Sol. In three dimensional flow, the equation of a streamline is given by –
▭(dx/u=dy/v=dz/w)
For 2D flow,
▭(dx/u=dy/v)

S10. Ans.(b)
Sol. Spherical shape of droplets of mercury is due to high surface tension because due to surface tension, it will try to minimize its surface area and mathematically sphere has minimum surface area.

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: Electrical Engineering 22 Oct 2020

Quiz: Electrical Engineering
Exam: SSC JE
Topic: Miscellaneous

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

Q1. Owing to skin effect
(a) current flows through the half cross-section of the conductor
(b) portion of the conductor near the surface carries more current and core of the
conductor carries less current
(c) portion of the conductor near the surface carries less current and core of the
conductor carries more current
(d) any of the above

Q2. The speed regulation of a synchronous motor is always
(a) positive
(b) zero
(c) negative
(d) 100%

Q3. An induction motor and a synchronous motor are connected to a common feeder line;
To operate the feeder line at unity p.f., the synchronous motor should be
(a) normally excited
(b) under-excited
(c) over-excited
(d) none of the above

Q4. A synchronous condenser (or capacitor) means
(a) synchronous motor operating at no-load
(b) over-excited synchronous motor with capacitor
(c) under-excited synchronous motor
(d) none of the above

Q5. A synchronous capacitor is used to
(a) improve p.f. of the system
(b) reduce losses in the system
(c) improve voltage regulation
(d) achieve all of above

Q6. n similar resistors each of resistance r when connected in parallel have the total
resistance R. When these resistances are connected in series, the total resistance is
(a) nR
(b) R/n²
(c) n²R
(d) R/n

Q7. Fig. shows part of a closed circuit. What is the value of VA–VB?

(a) 12 V
(b) 9 V
(c) 18 V
(d) 6 V

Q8. A wire of resistance 0.1 Ω /cm is bent to form a square ABCD of side 10 cm. A similar
wire is connected between B and D to form the diagonal BD. If a 2 V battery of negligible
internal resistance is connected between A and C, then total power dissipated is
(a) 2 W
(b) 3 W
(c) 4 W
(d) 6 W

Q9. In a power station,
(a) Reserve capacity = Plant capacity + Max. demand
(b) Reserve capacity = Plant capacity – Average demand
(c) Reserve capacity = Plant capacity – Max. demand
(d) Reserve capacity = Plant capacity + Average demand

Q10. In a 3-phase system, the line losses are
(a) directly proportional to cos ϕ
(b) inversely proportional to cos ϕ
(c) inversely proportional to cos² ϕ
(d) none of the above

SOLUTIONS
S1. Ans.(b)
Sol. The distribution of current over the cross section of the conductor is uniform in DC
only. In alternating current flow through a conductor does not distribute uniformly but it
will concentrate near the surface of the conductor. In fact, in AC system no current flow
through the core because the whole current will flow through the surface region. Due to
this reason the effective area of conductor is reduced causing an increase in AC resistance
. The effective AC resistance is usually referred as the effective resistance of the conductor
.This phenomenon is called the Skin effect as it will cause concentration of current at the
skin of conductor.

S2. Ans.(b)
Sol. The speed of a synchronous motor is constant (= synchronous speed, N_s) from no
load to full-load. Therefore, speed regulation of a synchronous motor is always zero

S3. Ans.(c)
Sol. An over-excited synchronous motor (i.e.E_b>V) takes power with a leading power
factor and behaves like a capacitor,

S4. Ans.(a)
Sol. A synchronous motor operating at no-load is called a synchronous capacitor or
condenser. It is specially designed for power factor control and has no external shaft.

S5. Ans.(d)
Sol.

S6. Ans.(c)
Sol. In parallel,
R=r/n→r=nR
In series,
R_eq=nr=n²R

S7. Ans.(b)
Sol.

V_AB=3+3×2=9V

S8. Ans.(c)
Sol.

This is a wheat stone bridge in balanced form.
∴ R_eq between A and C
R_eq=(2‖2)=1Ω
∴ Total power =V^2/R= 4/1=4 W

S9. Ans.(c)
Sol. Reserve capacity = Plant capacity – Max. demand

S10. Ans.(c)
Sol. Line current, IL=P/(√3 〖 V〗L cos⁡ϕ )
Since line losses are proportional to the square of I_L, it follows that line losses are proportional to 1/cos² ϕ

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: Electrical Engineering 21 Oct 2020

Quiz: Electrical Engineering
Exam: RSMSSB-JEn
Topic: Miscellaneous

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

Q1. In a three-phase system, the relation V_L=V_ph is applicable to a ________.
(a) star-connected without neutral point
(b) star-connected load
(c) single-phase system also
(d) delta-connected load

Q2. In a star connected three-phase balanced system. If the line current is 125A then the phase current is?
(a) 216.5 A
(b) 72.16 A
(c) 250 A
(d) 125 A

Q3. A 8-pole lap-wound generator has 400 conductors; the e.m.f. induced per conductor
being 5 V. The generated voltage of the generator is ………
(a) 60 V
(b) 1500 V
(c) 360 V
(d) 250 V

Q4. The curve B in Fig. below is the external characteristic of a ……… generator.

(a) shunt
(b) series
(c) flat-compounded
(d) under-compounded

Q5. Out of the following, ……… wave is the peakiest.
(a) sinusoidal
(b) square
(c) rectangular
(d) triangular

Q6. When a 15-V square wave is connected across a 50-V a.c. voltmeter, it will read ………
(a) 15 V
(b) 15×√2 V
(c) 15/√2 V
(d) none of the above

Q7. An alternating voltage υ=200 √2 sin 100 t is connected to a 1 μ F capacitor
through an a.c. ammeter. The reading of the ammeter shall be
(a) 40 mA
(b) 80 mA
(c) 100 mA
(d) 20 mA

Q8. A choke is preferred to a resistance for limiting current in an a.c. circuit because
(a) choke is cheap
(b) there is no wastage of energy
(c) current becomes wattless
(d) current strength increases

Q9. The value of current ‘I’ is flowing in the 1Ω resistor in the circuit shown in the figure
below will be

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

Q10. The no load speed of DC series motor is
(a) very small
(b) medium
(c) very high
(d) small

SOLUTIONS
S1. Ans.(d)
Sol. for delta connection –
Line voltage (VL )= Phase voltage (Vph)
Line current (IL) = √3× Phase current (Iph )

S2. Ans.(d)
Sol. for star (Y) – connection: –
Line current (IL) = Phase current (Iph )
Line voltage (VL )=√3×Phase voltage (Vph )
Or, phase voltage = (Line voltage)/√3
⇒ ▭(Vph=VL/√3) – For star connection
S3. Ans.(d)
Sol. No of conductors per parallel path
=400/8=50
∴ Eg=50×5=250 V

S4. Ans.(c)
Sol. Flat-compounded. (voltage regulation=zero)

S5. Ans.(d)
Sol. That wave is peakiest which has the greatest form factor (triangular wave).
The Form Factor for the various sinusoidal waveforms are as follows:
For a sine wave, it is π/2√2 = 1.11072073
For a half-wave rectified sine wave, it is π/2 = 1.5707963
For a full-wave rectified sine wave, it is π/2√2 = 1.11072073
For a square wave, it is equal to 1
For triangle waveform, it is 2/√3 = 1.15470054
For sawtooth waveform, it is 2/√3 = 1.15470054

S6. Ans.(a)
Sol. A voltmeter records the r.m.s. value and the r.m.s. value of 15-V square wave is 15 V.

S7. Ans.(d)
Sol. V(r.m.s.)=Vm/√2=200 √2 /√2=200V; ω=100 rad/s; X_C=1/ωC=1/(100×1×10^(-6) )=10^4 Ω
∴ I(r.m.s.)=V(r.m.s.)/X_C =200/10^4 =20×10^(-3) A=20 mA

S8. Ans.(b)
Sol. In an AC circuit, the coil of high inductance and negligible resistance used to control current, is called the choke coil. The power factor of such a coil is given by
cos⁡φ=R/√(R^2+ω^2 L^2 )≈ R/ωL (as R <<<ωL).
cos⁡φ is very small. Thus, the power absorbed by the coil is very small. The only loss of energy is due to hysteresis in the iron core, which is much less than the loss of energy in the resistance that can also reduce the current if placed instead of the choke coil.

S9. Ans.(c)
Sol.
Method-1: From ohm’s law, if we know the voltage across a resistor, then we can determine the current through resistor R as I=V/R.
Here, V = 5 V (constant)
So, I=5/1 = 5A

Note: The voltage across any current source is purely arbitrarily. The voltage across it depends purely upon the voltage source connected in parallel across it. Hence, in present case voltage across the current source = 5 V.
Method2:
Applying superposition theorem:
Current due to 5 V source: current source open circuit & I=5/1=5 A
Current due to 5 A source: voltage source short circuit and current flows through short-circuit. So, current through 1-ohm resistor=0 A
∴I_TOTAL=5+0=5 A

S10. Ans.(c)
Sol. The load-speed curve of DC series motor is shown below.

It is clear that the speed of the DC series motor at no load is very high. So, it is never stared at no load.

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: Civil Engineering 20 Oct 2020

Quiz: Civil Engineering
Exam: SSC-JE
Topic: Strength of Material

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

Q1. The shape of Bending Moment Diagram in a beam subjected to only Uniformly Distributed Load (UDL) is :
(a) Parabola
(b) Triangular
(c) Constant
(d) Cubic parabola

Q2. The ratio of normal stress to normal strain within elastic limits is called :
(a) Poisson’s Ratio
(b) Bulk Modulus
(c) Young’s Modulus
(d) Shear Modulus

Q3. The slenderness ratio of a column is zero when its length :
(a) is equal to its radius of gyration
(b) is supported on all sides throughout its length
(c) Effective length is equal to Actual length
(d) is very large

Q4. A material has identical properties in all directions, it is said to be
(a) homogeneous
(b) isotropic
(c) elastic
(d) orthotropic

Q5.The maximum bending moment in a simply supported beam subjected to point load occurs at :
(a) Supports
(b) Mid span
(c) Quarter span
(d) Under point load

Q6. For a given elastic material, the elastic modules E is 210 GPa and its Poisson’s Ratio is 0.27. What is the approximate value of its modules of rigidity?
(a) 105 GPa
(b) 83 GPa
(c) 159 GPa
(d) 165 GPa

Q7. If a ductile material is subjected to a unidirectional tensile force, then to avoid shear failure, the material should have its shear strength at least equal to
(a) its tensile strength
(b) Half the tensile strength
(c) Its compressive strength
(d) Twice the tensile strength

Q8. Find the tensile stress of a mild steel rod of 18mm diameter. Given: ultimate load = 9.0 ton.
(a) 0.03 Ton/sq.mm
(b) 0.02 Ton/sq.mm
(c) 0.05 Ton/sq.mm
(d) 0.06 Ton/sq.mm

Q9. A column that fails due to direct stress, is called:
(a) short column
(b) long column
(c) weak column
(d) medium column

Q10. A solid metal bar of uniform diameter D and length L is hung vertically from a ceiling. If the density of the material of the bar is P and the modulus of elasticity is E, then the total elongation of the bar due to its own weight is
(a) PL/2E
(b) PL²/2E
(c) PE/2L
(d) PE/2L²

SOLUTIONS

S1. Ans.(a)

Sol. Shape of bending moment diagram-

No load – Rectangular

Point load – Triangular

Uniformly distributed load – Parabola (2° curve)

Uniformly varying load (UVL) – Cubic parabola (3° curve)

S2. Ans.(c)
Sol.
▭(Young^’ s modulus of elasticity (E)=(Normal stress)/(Normal strain))

▭(Shear Modulus (G)=(Shear stress)/(Shear strain))

S3. Ans.(b)
Sol. if a column is supported on all sides throughout its length then the value of unsupported length of the column is zero so that the slenderness ratio is also zero.

S4. Ans.(b)
Sol. A material is said to be isotropic when it has identical properties in all direction and a material is said to be homogenous when it has same property at each cross-section.

S5. Ans.(d)
Sol. The maximum bending moment in a simply supported beam of length L subjected to a point load ‘W’ occurs at under point load and the magnitude of maximum bending moment will be WL/4.

S6. Ans.(b)
Sol. Given, Elastic modulus (E) = 210 GPa
Poison ratio (μ) = 0.27
Modulus of rigidity (G) = ?
E = 2G(1+μ)
G =E/2(1+μ)
=210/2(1+0.27)
▭(G=82.67 GPa≈83 GPa)

S7. Ans.(d)
Sol. if ductile material is subjected to a unidirectional tensile force, then to avoid shear failure material should have its shear strength is twice the tensile strength.

S8. Ans.(a)
Sol. Diameter = 18 mm
Ultimate load = 9.0 ton
Tensile stress = (9.0 ton)/(π/4×18²)
= 0.035 ton/mm²

S9. Ans.(a)
Sol. The short column fails primarily due to direct stress because in short column the buckling stresses are very small compared to direct stresses.

S10. Ans.(b)
Sol. The elongation of bar due to its own weight (w) is
∆=WL/2AE
Now W = PAL
∴ ∆ =PL²/2E

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: Electrical Engineering 19 Oct 2020

Quiz: Electrical Engineering
Exam: SSC-JE
Topic: Miscellaneous

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

Q1. Determine the self-inductance (in mH) of a 3m long-air cored solenoid, when the coil has 300 turns and the diameter of the coil is 12 cm.
(a) 0.24
(b) 0.32
(c) 0.35
(d) 0.42

Q2. Determine the reluctance (in Amp-turn/Wb) of a coil when the flux through the coil is 25 Wb and the value of produced mmf is 50 Amp-turns.
(a) 2
(b) 4
(c) 6
(d) 8

Q3. A current of 3A through a coil sets flux linkage of 15 Wb-turn. The inductance of the coil is?
(a) 1 H
(b) 3 H
(c) 5 H
(d) 15 H

Q4. Which of the following is bilateral element?
(a) Constant voltage source
(b) Constant current source
(c) Capacitance
(d) All of the above

Q5. In the following circuit, the equivalent capacitance between terminals A and B is

(a) C
(b) C/2
(c) 2C/3
(d) 3C/2

Q6. Which of the following materials has susceptibility independent of temperature?
(a) Ferromagnetic
(b) Ferrimagnetic
(c) Paramagnetic
(d) Diamagnetic

Q7. Determine the capacitive susceptance (in siemens) of a circuit if the capacitor of the circuit is 0.08 mF and supplied with a 50 Hz frequency.
(a) O.025
(b) 0.064
(c) 0.046
(d) 0.034

Q8. Which of the following is an effect of non-uniform current distribution in a conductor?
(a) Skin effect
(b) Ferranti effect
(c) Proximity effect
(d) Skin effect or proximity effect

Q9. A transformer has iron loss of 900 W and copper loss of 1600 W at full load. At what percentage of load will the efficiency be maximum?
(a) 133
(b) 125
(c) 75
(d) 66.66

Q10. A transformer is working at full load with maximum efficiency. Its iron loss is 1000 W. What will be its copper loss at half full load?
(a) 2000 W
(b) 1000 W
(c) 500 W
(d) 250 W

SOLUTIONS
S1. Ans.(d)
Sol. Given that, N=300 turns
d= 12 cm ⇒r=d/2=6 cm=0.06 m
l= 3m
for solenoid, L=(µ0 µr N^2 A)/l=(4π×10^(-7)×1×300×300×π×〖(0.06)〗^2)/3=0.42 mH
NOTE: for air µ_r=1
And µ_0=4π×10^(-7)H/m ≈ 12.57×10−7 H/m

S2. Ans.(a)
Sol. MMF produced in a coil=NI=Reluctance×ϕ
∴NI=Reluctance×ϕ
⇒reluctance=NI/ϕ=50/25=2 AT/Wb

S3. Ans.(c)
Sol. inductance of coil=L=Nϕ/I=15/3=5 H

S4. Ans.(c)
Sol. Bilateral elements are defined as the elements through which magnitude of current is independent of polarity of supply voltage.
e.g. of bilateral elements: resistors, inductors, capacitors

S5. Ans.(a)
Sol.

⇒C_AB=((C×C)/(C+C))+C/2=C/2+C/2=C

S6. Ans.(d)
Sol. Diamagnetic material: Magnetic materials which align against the magnetic field are known as diamagnetic materials. Magnetic susceptibility is χ<0 which means it is always a negative value for diamagnetic material.
These materials are independent of temperature. As these materials magnetize in the opposite direction, they do have a small amount of magnetization intensity. Gold, tin, mercury, water, etc are examples of diamagnetic materials.
For a diamagnetic material, the relative permeability lies between 0 ≤ μr < 1 and its susceptibility lies between −1< χ< 0. 𝑥=𝑢𝑟−1
Where 𝑥 is a dimensionless quantity defines as the magnetic susceptibility of the medium.

S7. Ans.(a)
Sol. capacitive susceptance(B)=1/XC =1/((1/2πfC) )
∴B==2πfC=2×3.14×50×0.08×10^(-3)=0.025 siemens

S8. Ans.(d)
Sol. Skin effect: When an Alternating Current flows through a conductor, it is not distributed uniformly throughout the conductor cross-section. AC current has a tendency to concentrate near the surface of the conductor. This phenomenon in alternating currents is called as the skin effect.
Proximity effect:
When two or more conductors carrying alternating current are close to each other, then distribution of current in each conductor is affected due to the varying magnetic field of each other. when the nearby conductors carrying current in the same direction, the current is concentrated at the farthest side of the conductors. When the nearby conductors are carrying current in opposite direction to each other, the current is concentrated at the nearest parts of the conductors. This effect is called as Proximity effect.

S9. Ans.(c)
Sol. maximum efficiency in %=√((iron loss(Pi))/(full load cu-loss(Pcu)) )×100=√(900/1600) ×100=75 % of full-load

S10. Ans.(d)
Sol. For maximum efficiency, Copper loss (Pc) = Iron losses (Pi) = 1000 W
And P_cu (x)=x^2×Pcu (full-load)
∴P_(cu(half-load))= (1/2)^2 P(cu(full-load))=1/4×1000=250 W

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.