Electrical Engineering Practice Impotent Questions Part 5

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54-The function of the starter of the DC motor is:

A. To limit the starting current

B. To limit the starting voltage

C. To increase the field resistance

D. To reduce armature resistance

Ans: A. To limit the starting current

55-A battery consists of 44 2-volt cells, each with an internal resistance of 0.12 ohm. The voltage of each cell has fallen to 1.8 volt. It is a requirement to charge the battery at a constant current of 4 A from a charger with an internal resistance of 2 ohm. The Applied voltage at the commencement of charge is:

A.

B.

C.

D.

E.

Ans: C.

56-The ratio of starting torque to full load torque is minimum in:

A. Shunt motor

B. Series motor

C. Differential compound motor

D. Commutative compound motor

Ans: A. Shunt motor

57-Photon always propagate with speed c, but light comes into view to travel at a speed diverse from c in an opaque medium. We can explain this fact by … in medium by introducing a phase change upon re-radiation.

A. Electron oscillators

B. Discharge Tube

C. Cathode rays

D. Electro-magnetic rays

Ans: B. Discharge Tube

58-Frog leg winding is:

A. Same as simplex winding

B. Same as duplex winding

C. Combined lap and wave winding on a single rotor

D. Duplex wave winding on a single rotor

Ans: C. Combined lap and wave winding on a single rotor

59-In periodic table, semiconductors belong to:

A. Third group

B. Fourth group

C. Fifth group

D. First group

And: B. Fourth group

60-In a DC machine with interpoles, to get improved commutation, the brush shift angle must be:

A. Varied with change in load

B. Kept constant

C. Zero degree

D. 100 degree

And:

61-If the step response of an initially relaxed system is known, then the ramp response can be obtained by:

A. Integrating the step response

B. Differentiating the step response twice

C. Integrating the step response twice

D. Differentiating the step response

Ans: A. Integrating the step response

62-Eddy current losses in a DC machine are given by BftV where V stands for:

A. Voltage generated

B. Peripheral velocity

C. Linear velocity of conductors

D. Volume of iron part

Ans: D. Volume of iron part

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