# SSC JE Electrical MCQ Questions

### 1. If in an R-L-C series circuit the current lags the applied voltage by 60° then

(a) XL – XC = R/√3
(b) XL – XC = √3R
(c) XL = XC = R
(d) XL – XC = R

(a) 5 W
(b) 10 W
(c) 2 W
(d) 1 W

(a) |Z2| = |Z1|
(b) Z2 = Z1
(c) Z2* = -Z1
(d) Z2 = Z1*

(a) 1/4π√3
(b) 1/4π√2
(c) 1/4π
(d) 1/4π√10

(a) 22.36 A
(b) 17.32 A
(c) 8.165 A
(d) 14.14 A

### 6. Two incandescent bulbs of rating 230 V, 100 W and 230 V, 500 W are connected in parallel across the mains. As a result what will happen?

(a) 100 W bulb will glow brighter
(b) 500 W bulb will glow brighter
(c) Both the bulbs will glow equally bright
(d) Both the bulbs will glow dim

### 7. In two wattmeter method of measurment of threephase power of a balanced load, if both the wattmeters indicate the same reading, then the power factor of the load is

(a) 0.5 lagging
(b) less than 0.5 lagging
(c) unity
(d) greater than 0.5 lagging

### 8. Measurement of ________ is affected by the presence of thermo-emf in the measuring circuit

(a) high resistance
(b) low resistance
(c) capacitance
(d) inductance

### 9. The response time of an indicating instrument is determined by its

(a) deflecting system
(b) damping system
(c) controlling system
(d) support type to the moving system

### 10. The ratio of the reading of two wattmeters connected to measure active power in a balanced 3-phase load is 2 : 1. The power factor of the load is

(a) 0.866 lag
(d) None of the above

(a) 1.18 kW
(b) 2.36 kW
(c) 0.18 kW
(d) 0.36 kW

(a) 11 W, 20 W
(b) 30 W, 45 W
(c) 16 W, 30 W
(d) 22 W, 40 W

### 13. The voltage wave given by v = 4coswt produces a current wave i =1.5coswt – 2.598sinwt in a circuit. The current wave

(a) leads voltage wave by 60°
(b) lags voltage wave by 60°
(c) leads voltage wave by 30°
(d) lags voltage wave by 30°

### 14. The damping in D’Arsonval galvanometer is obtained by

(a) a shunt connected across moving coil
(b) eddy current induced in metal discs
(c) fluid friction
(d) employing springs

(a) θ
(b) θ2
(c) 1/θ
(d) Sin θ

### 16. The range of a DC milliammeter can be extended by using a

(a) low resistance in series
(b) low resistance shunt
(c) high resistance in series
(d) high resistance shunt

(a) resistive
(b) inductive
(c) capacitive
(d) reactive

### 18. A DC shunt generator builds upto 230 V. Other conditions remaining same, if only the residual magnetism of the original machine is reversed, the voltage to which the generator will build up is

(a) 230 V with brush polarity reversed
(b) 230 V with brush polarity same
(c) somewhat less than 230 V with brush polarity reversed
(d) somewhat less than 230 V with brush polarity same

(a) 781.25 watt
(b) 1250 watt
(c) 1562.5 watt
(d) 12500 watt

### 20. If a 3-phase induction motor hums during starting up, the probable cause could be

(a) unequal stator phase resistance
(b) open circuited rotor
(c) interturn short circuit on rotor
(d) any of the above

### 21. In a 3-phase synchronous generator, the stator winding is connected in star, because a delta connection would

(a) have circulating currents due to triple harmonics
(b) require more insulation and conductor material
(c) require larger conductor and more core material
(d) result in a short circuit

(a) 50%
(b) 62.3%
(c) 70.7%
(d) 100%

### 23. The torque developed in a DC series motor in unsaturated magnetic circuit condition is

(a) almost practically constant at all load currents
(b) require more insulation and conductor material
(c) require large conductor and more core material
(d) require in a short circuit

(a) 30 Nm
(b) 240 Nm
(c) 84 Nm
(d) 120 Nm

### 25. An alternator has rated field current of 3 A. It is developing 180 V at a field current of 1.5 A at rated speed. If its field current is made 3 A rated speed, then the generated voltage would be

(a) 360 V
(b) 180 V
(c) less than 360 V
(d) 270 V

(a) 30-45%
(b) 55-70%
(c) 5-10%
(d) 85-95%

### 27. In which of the following industries, are all the motors totally enclosed and moisture proof ?

(a) Iron and steel industry
(b) Sugar industry
(c) Paper industry
(d) Textile industry

(a) 2.81 kW
(b) 1.26 kW
(c) 2812 kW
(d) 3032 kW

### 29. In suspension type insulator the potential drop is

(a) maximum across the lowest disc
(b) maximum across the topmost disc
(c) maximum across the disc at the midpoint of the string
(d) uniformly distributed across the string

### 30. Of the following water turbines, which is not a reaction turbine ?

(a) Pelton wheel
(b) Kaplan turbine
(c) Propeller turbine
(d) Francis turbine

### 32. Sheaths are used in underground cables to

(a) provide proper insulation
(b) provide mechanical strength
(c) protect the cable from moisture
(d) none of the above

### 33. If the frequency of a transmission system is changed from 50 Hz to 100 Hz, the string efficiency

(a) will increase
(b) will decrease
(c) remains unchanged
(d) may increase or decrease depending on the line parameters

### 34. The power station where coal is used as a fuel is called

(a) terrestrial power station
(b) thermal power station
(c) solar power station
(d) nuclear power station

### 35. Making capacity of a circuit breaker is equal to

(a) 2.55 times symmetrical breaking current
(b) 1.5 times symmetrical breaking current
(c) √2 times symmetrical breaking current
(d) symmetrical breaking current

(a) 25%
(b) 33.33%
(c) 66.67%
(d) 75%

(a) 1.0
(b) 0.7
(c) 0.6
(d) 0.5

### 38. Resistance switching is normally employed in

(a) all types of circuit breakers
(b) bulk oil circuit breakers
(c) minimum oil breakers
(d) air blast circuit breakers

### 39. Which one is the disadvantage of oil when used as an arc extinguishing medium in the oil circuit breaker

(a) During arcing, oil produces carbon particles
(b) During arcing, oil produces hydrogen gas
(c) Oil provides insulation to the live exposed contacts from the earthed parts of the breaker
(d) Oil provides good insulation between the fixed and moving contacts

(a) 1.25
(b) 0.80
(c) 1.77
(d) 2.5

### 41. During arc extinction SF6 gets

(a) decomposed into  SF4 and SF2
(b) decomposed into S and F ions
(c) reduced to SF2
(d) oxidised

### 42. Sparking between the contacts of a circuit breaker can be reduced by inserting

(a) a capacitor in parallel with the contacts
(b) a capacitor in series with the contacts
(c) a resistor in the line
(d) a reactor in the line

(a) 50 kV
(b) 57 kV
(c) 60 kV
(d) 100 kV

### 44. Which of the following materials for heating element should be selected if a furnace is to be used for heating upto temperature around 1500oC ?

(a) Eureka
(b) Kanthal
(c) Platinum-molybdenum carbon compound
(d) Nichrome

### 45. The type of DC generator used for arc welding should be a

(a) series generator
(b) shunt generator
(c) cumulatively compounded generator
(d) differentially compounded generator

(a) 10.05 V
(b) 1.5 V
(c) 1.05 V
(d) 0.5 V

### 47. By increasing the transmission voltage to double of its original value the same power can be despatched keeping the line loss

(a) equal to its original value
(b) half the original value
(c) double the original value
(d) one-fourth of original value

### 48. Which of the following is true ?

(a) Load factor = capacity factor ´ utilization factor
(b) Utilisation factor = capacity factor ´ load factor
(c) Capacity factor = load factor + utilisation factor
(d) Capacity factor = Load factor ´ utilisation factor

(a) 7.32 kVAR
(b) 10 kVAR
(c) 27.32 kVAR
(d) 10.32 kVAR

### 50. The most appropriate way of mitigating the problem of interference between power line and commutation line is to

(a) transpose the power line
(b) transpose the communication line
(c) use double circuit power line
(d) use bundled conductor power line