SSC JE Electrical MCQ

21. To maximize the driving torque in an induction type instrument, flux produced by shunt coil and series coil should be

(a) in phase with each
(b) in quadrature with each other
(c) displaced by 45° with respect to each other
(d) out of phase with respect to each other

22. To minimize the errors due to lead and contact resistances, low resistances used in electrical measurement work are provide with

(a) guard rings
(b) four terminals
(c) thick insulation
(d) metal shields

23. Examine the two statements ‘A’ and ‘R’ and select your answer

Statement A : Switching of a lamp in house produce noise in a radio.
Statement R : Switching operation produces are across separating contacts
(a) Both A and R are true and R is a correct explanation of A
(b) Both A and R are true and R is not correct explanation of A
(c) A is true but R is false
(d) A is false but R is true

24. The small pockets of air in the high voltage cable provide________relative permittivity _________ electric field and at these sites breakdown is likely to be initiated

(a) high, high
(b) low, low
(c) low, high
(d) high, low

25. The capacitance measured between any two cores of a 3-core cable with the sheated earthed is 3µF . The capacitance per phase will be

(a) 15µF
(b) 6µF
(c) 1µF
(d) None of the above

26. In an insulated cable having core diameter d and overall diameter D, the ratio of maximum to minimum dielectric stress is given by

(a) (D/d)^1/2
 (b) (D/d)²
(c) D/d
(d) d/D

27. Compared to the breaking capacity of a circuit breaker, its making capacity should be

(a) more
(b) less
(c) equal
(d) the two are unrelated to each other

28. In electronic circuits, for blocking the DC component of a voltage signal, a/an _________ is connected is series with the voltage source

(a) capacitor
(b) diode
(c) resistor
(d) inductor

29. For n-type semiconductor, the doping material is

(a) tetravalent
(b) pentavalent
(c) trivalent
(d) bivalent

30. A attenuator probe as shown, is connected to an amplifier of input capacitance 0.1 μF. Value of C that must be connected across 100 k to make the overall gain independent of frequency, is

(a) 0.01 µF
(b) 0.1 µF
(c) 1 µF
(d) 10 µF

31. Silicon content in iron lamination is kept within 5% as it

(a) makes the material brittle
(b) reduces the curie point
(c) increased bysteresis loss
(d) increased cost

32. A wattmeter is marked 15A/30A, 300V/600V and its scale is marked up to 4500 watts. When the meter is connected for 30A, 600A, the point indicated 2000 watts. The actual power in the circuit is

(a) 2000 watts
(b) 4000 watts
(c) 6000 watts
(d) 8000 watts

33. Resistance switching is normally employed in

(a) bulk oil brakers
(b) minimum oil breakers
(c) air blast circuit breakers
(d) all of (a), (b) and (c)

34. If the angular frequency of an alternating voltage is w, then the angular frequency of instantaneous real power absorbed in an ac circuit is

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

35. If the transistor having VCE = 5 V, VBE = 0.7 has beta = 45, value of R is

(a) 85.64 k
(b) 63.14 k
(c) 72.15 k
(d) 91.18 k

36. In a balanced 3-phase circuit, the line current is 12 A. When the power is measured by two wattmeter method, one meter reads 11kW while the other reads zero. Power factor of the load is

(a) 0
(b) 0.5
(c) 0.866
(d) 1.0

37. In case of frosted GLS lamps, frosting is done by

(a) Acid etching
(b) ammonia
(c) ozone
(d) salt water

38. If the supply polarity to the armature terminals of a separately excited DC motor is reversed, the motor will run under

(a) Plugging condition
(b) Regenerative braking condition
(c) Dynamic braking condition
(d) Normal motoring condition

39. For welding purpose, the secondary of transformer used should be capable of carrying

(a) high voltage, high current
(b) high voltage, low current
(c) low voltage, high current
(d) low voltage, low current

40. Which of the following is correct ?

(a) Load factor = capacity factor x utilisation factor
(b) Utilisation factor = capacity factor x load factor
(c) Capacity factor = load factor x utilisation factor
(d) Load factor has no relation with capacity factor and utilisation factor