SSC JE Electrical Important MCQ Part 18


SSC JE Electrical Important MCQ PDF Part 18

1.How much voltage will be measured across the resistor in Figure

A.280 V
B.280 mV
C.400 V
D.56 mV

Answer  : B (V= IR =5 mA×56 Ohms=5×10⁻³×56 = 280 mV)

2.An alternating voltage is represented by the expression v=35 sin(314.2 t ) volt.The period of the waveform is


A.50 ms
B.20 ms
C.50 s
D.20 s

Answer  : B

(v=35 sin(314.2t) volt and comparing this to the standard v=Vm sin (2πft) volt we get 2πft=314.2
So f=314.2/2π=50 Hz
T=1/f=1/50 second=20 ms)

3.A sinusoidal alternating voltage has an average value of 3.5 V and a period of 6.67 ms.The standard expression for voltage will be

A.v=3.5 sin(314.2t)
B.v=5.5 sin(300πt)
C.v=5.5 sin(94.2t)
D.v=3.5 sin(30πt)

Answer  : B

(Vav=3.5 V,T=6.67×10⁻³ s
Vav=0.637 Vm
So Vm=Vav/0.637=3.5/0.367=5.5 V
f=1/T=1/6.67×10⁻³ Hz=150 Hz
The standard expression is of the form v=Vm sin (2πft) volt
v=5.5 sin(2π×150×t)
v=5.5 sin(300πt) volts )

4.A non-sinusoidal waveform has a peak factor of 2.5, and an r.m.s. value of 240 V,The maximum value of voltage is

A.1.414 V
B.200 V
C.600 V
D.240 V

Answer  : C (Peak factor=maximum value/r.m.s. value So maximum value Vm= Peak factor×r.m.s.=2.5×240=600 V)

5.A battery of emf 6 V has an internal resistance of 0.15 ohms .What is its terminal p.d. when delivering a current of 0.5 A

A.5.925 V
B.6.000 V
C.4.000 V
D.7.075 V

Answer  : A (E=6 V,r=0.15 ohms,V=E-Ir=6-(0.5*0.15)=6-0.075=5.925 V)

6.A current of 200 mA flows through a resistance of 750 ohms for a time of 5 minutes,What is the energy dissipated

A.90 kJ
B.9 kJ
C.800 J
D.80 kJ

Answer  : B (W=I²Rt=0.2×750×300=9000 J or 9 kJ)

7.A resistor of 680 ohms,when connected in a circuit, dissipates a power of 85 mW. Then current flowing through it

A.7.6 A
B.7.6 mA
C.11.18 mA
D.11.18 A

Answer  : C (P=I²R So I=√P/R=√85×10⁻³/680=√1.25×10⁻⁴=11.18 mA)

8.Symbol shown in figure of

A.Resistor
B.Potentiometer
C.Rheostat
D.SPDT switch

Answer  : B (A potentiometer is a three-terminal resistor with a sliding or rotating contact that forms an adjustable voltage divider. If only two terminals are used, one end and the wiper, it acts as a variable resistor or rheostat)

9.Through which resistor in Figure is there always current, regardless of the position of the switches

A.R₁
B.R₃
C.R₅
D.R₆

Answer  : C

10.The value of R₄ in the circuit of Figure is

A.56 Ω
B.56 kΩ
C.90 kΩ
D.90 Ω

Answer  : B

(From the ohmmeter reading,R total=146 kΩ
RT=R₄+R₁ + R₂ + R₃)
R₄ = RT – (R₁ + R₂ + R₃) = 146 kΩ – (10 kΩ + 33 kΩ + 47 kΩ) = 56 kΩ)

11.In three-phase transformer, maximum voltage regulation occurs at____________

A.Unity power factor
B.Rated KVA of transformer
C.Leading power factor
D.Lagging power factor

Answer  : D

12.In three phase star connection, line current is equal to _____________

A.Phase current
B.Phase current/√3
C.Phase voltage
D.Phase voltage/√3

Answer  : A

13.The resistance of shunt field 250 V DC shunt generator is 200 ohms. What will be the field current

A.0 .8 Amps
B.4.5 Amps
C.1.25 Amps
D.5 Amps

Answer  : C (If=250/200=1.25 Amps )

14.In DC generator, armature is laminated to reduce _______

A.Field flux
B.Copper loss
C.Eddy current loss
D.Differentially compound generator

Answer  : C

15.The 3 phase transformer used to transmit the voltage is connected in ——–

A.Star – Star
B.Delta – Delta
C.Delta – Star
D.Star – Delta

Answer  : C (Delta-Star transformers are common in commercial, industrial, and high-density residential locations, to supply three-phase distribution systems)

16.__________ relay is connected in the pipe connecting main tank of transformer and conservator.

A.Overcurrent
B.Distance
C.Buchholz
D.Directional

Answer  : C

17.What is the full form of XLPE Cable

A.Externally linked PVC ethylene
B.Cross linked poly ethylene
C.Externally linked poly ethylene
D.Cross linked PVC ethylene

Answer  : B

18.Energy meter is an example for which type of instrument

A.Pneumatic type
B.Recording type
C.Indicating type
D.Integrating type

Answer  : D (The integrating instrument measures the total energy supplied by the circuit in a given interval of time)

19.__________ is used for high switching frequency application.

A.TRIAC
B.MOSFET
C.SCR
D.Diode

Answer  : B

20.Which stepper motor gives high torque and low angular resolution

A.Variable resistance stepper motor
B.Variable reluctance stepper motor
C.Permanent magnet stepper motor
D.Variable inductance stepper motor

Answer  : C (The Permanent Magnet stepper motor produces more torque than the Variable Reluctance Stepper Motor,They have higher inertia and therefore, lower acceleration than variable stepper motors)

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