Electrical Online Test 32

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Attempt Free Electrical Online Test 32 Here. Read The Important Electrical MCQ From Below.

1) Open circuit test on a transformer is conducted to obtain

a. The leakage impedance’s
b. Eddy current loss only.
c. hysteresis loss only
d. Copper loss
Ans. d. Copper loss

2) When commutation is obtained by increasing the current density at the leading edge and decreasing the same at trailing edge, it is known as

a. Under commutation
b. Over commutation
c. Straight commutation
d. Sinusoidal commutation.
Ans. b. Over commutation

3) The number of commutator segments in a dc machine is equal to the no. of

a. Coil-sides
b. Turns
c. Coils
d. slots.
Ans. c. Coils

4) A wound rotor induction motor is preferred over squirrel cage induction motor when the major consideration involved is

a. High starting torque
b. Low starting current
c. Speed control over limited range
d. All of these
Ans. d. All of these

5) Which component of the no load current of the transformer is opposite in phase to the induced emf ?

a. Magnetizing component
b. Core loss component
c. Both of these
d. None of these
Ans. b. Core loss component

Electrical Online Test 32

6) When smooth and precise speed control over a wide range is desired, the motor preferred is

a. Synchronous motor
b. Squirrel cage induction motor
c. wound rotor induction motor
d. Dc motor.
Ans. d. Dc motor.

7) A universal motor operates on

a. constant speed and varying load
b. Constant load and varying speed
c. Approximately constant speed and load
d. Synchronous speed with varying load.
Ans. c. Approximately constant speed and load

8) The capacitance of a small single phase motor will be of the order of

a. Kilo farads
b. Few hundred farads
c. Farads
d. Micro or pico farads.
Ans. d. Micro or pico farads.

9) A motor suitable for signaling device is

a. induction motor
b. dc shunt motor
c. Dc series motor
d. reluctance motors.
Ans. d. reluctance motors.

10) Which of the following is preferred for automatic drives ?

a. Synchronous motors
b. Squirrel cage induction motor
c. Ward Leonard controlled dc motors
d. Any of these
Ans. c. Ward Leonard controlled dc motors

Electrical Online Test 32

11) In lap windings, the equalizer rings arc used to save

a. Armature winding from carrying circulating currents
b. Commutator from carrying circulating currents
c. Brushes from carrying circulating currents
d. Armature core from eddy currents.
Ans. c. Brushes from carrying circulating currents

12) Transformer action requires a

a. Constant magnetic flux
b. Increasing magnetic flux
c. Alternating magnetic flux
d. Alternating electric flux.
Ans. b. Increasing magnetic flux

13) In electrical machines the material preferred for pole shoes of electro-magnets is

a. Pure iron
b. Aluminum
c. Copper
d. Lead.
Ans. a. Pure iron

14) For ceiling fans generally the single phase motor used is

a. Split phase type
b. capacitor start type
c. Capacitor start and run type
d. Permanent capacitor type.
Ans. d. Permanent capacitor type.

15) The percentage of silicon in transformer stampings is usually limited to

a. 0.4%
b. 1.4%
c. 4%
d. 14%.
Ans. c. 4%

Electrical Online Test 32

16) Skewing of rotor slots helps in

a. Improving beat transfer
b. Reducing noise
c. Suppressing undesirable harmonics
d. All of these
Ans. c. Suppressing undesirable harmonics

17) Transformer-core lamination are made of

a. Cast iron
b. Wrought iron
c. Silicon steel
d. Cast steel.
Ans. c. Silicon steel

18) In dc machines the number of poles is generally decided by

a. frequency of flux reversals
b. Weight of iron parts
c. Weight of copper
d. All of these
Ans. d. All of these

19) When V is the voltage applied across the insulation, the dielectric loss for an insulating material will be proportional to

a. V
b. V2
c. 1/ V
d. 1/ V2
Ans. b. V2

20) The direction of rotation of universal motor can be reversed by

a. Reversing the supply terminals
b. Switching over from ac to dc
c. Interchanging the brush leads
d. Any of these
Ans. c. Interchanging the brush leads

Electrical Online Test 32

21) The motor used for driving the record player deck is

a. dc series motor
b. Synchronous motor
c. Hysteresis motor
d. dc shunt motor.
Ans. c. Hysteresis motor

22) The motor normally used for crane travel is

a. AC slip ring motor
b. Ward Leonard controlled DC shunt motor
c. Synchronous motor
d. DC differentially compound motor.
Ans. a. AC slip ring motor

23) Iron losses of a machine are

a. Directly proportional to flux density
b. Directly proportional to the square of flux density
c. inversely proportional to flux density
d. Inversely proportional to the square of flux density.
Ans. a. Directly proportional to flux density

24) The electric breakdown strength of an instating material depends on

a. Composition of the material
b. Thickness of the material
c. Time of application of voltage
d. All of the above.
Ans. d. All of the above.

25) In portable tools the speed of the driven shaft is reduced by

a. Gearing
b. Belt drive
c. Chain drive
d. Fluid coupling
Ans. a. Gearing

Electrical Online Test 32