21. The function of a commutator in a d.c. generator is
a) to collect current from conductors.
b) to change d.c. to a.c.
c) to conduct the current to the brushes.
d) to change a.c. to d.c.
ans. d
22. The current flowing in the conductors of a d.c. motor is
a) a.c.
b) d.c.
c) a.c as well as d.c.
d) transients.
ans. a
23. As the load is increased the speed of a d.c. shunt motor will
a) remain constant.
b) increase proportionately.
c) increase slightly.
d) reduce slightly.
ans. d
24. If the current in the armature of d.c. series motor is reduced to 5% , the torque of the motor will become
a) 50% of the previous value.
b) 25% of the previous value.
c) 150% of the previous value.
d) 125% of the previous value.
ans. b
25. In d.c. shunt motor, if the terminal voltage is reduced to half and torque remains the same. then,
a) speed will be half and armature current also will be half.
b) speed will be half but armature current remains the same.
c) speed will be half and armature current becomes double.
d) speed and armature current will remain the same.
ans. c
26. One d.c.motor drives another d.c.motor . The second d.c. motor when excited and driven,it
a) runs
b) does not run as generator.
c) runs as a generator
d) also runs as a motor.
ans. c
27. A 4-pole lap-wound armature has 480 conductors and a flux per pole of 25 m Wb. The emf generated, when running at 600 rpm, will be
a) 240 V
b) 120 V
c) 60 V
d) 30 V
ans. b
28. The torque of a motor is
a) force is N-m acting on the rotor.
b) the product of tangential force on the motor and its radius.
c) the electrical power in kW.
d) the power given to load being driven by the motor
ans. b
29. The armature current drawn by any d.c. motor is proportional to
a) the voltage applied to the motor.
b) the torque required .
c) the flux required in the motor.
d) the speed of the motor.
ans.
30. The output power of any electrical motor is taken from
a) the armature
b) the coupling mounted on the shaft
c) the conductors.
d) the poles.
ans. b
a) to collect current from conductors.
b) to change d.c. to a.c.
c) to conduct the current to the brushes.
d) to change a.c. to d.c.
ans. d
22. The current flowing in the conductors of a d.c. motor is
a) a.c.
b) d.c.
c) a.c as well as d.c.
d) transients.
ans. a
23. As the load is increased the speed of a d.c. shunt motor will
a) remain constant.
b) increase proportionately.
c) increase slightly.
d) reduce slightly.
ans. d
24. If the current in the armature of d.c. series motor is reduced to 5% , the torque of the motor will become
a) 50% of the previous value.
b) 25% of the previous value.
c) 150% of the previous value.
d) 125% of the previous value.
ans. b
25. In d.c. shunt motor, if the terminal voltage is reduced to half and torque remains the same. then,
a) speed will be half and armature current also will be half.
b) speed will be half but armature current remains the same.
c) speed will be half and armature current becomes double.
d) speed and armature current will remain the same.
ans. c
26. One d.c.motor drives another d.c.motor . The second d.c. motor when excited and driven,it
a) runs
b) does not run as generator.
c) runs as a generator
d) also runs as a motor.
ans. c
27. A 4-pole lap-wound armature has 480 conductors and a flux per pole of 25 m Wb. The emf generated, when running at 600 rpm, will be
a) 240 V
b) 120 V
c) 60 V
d) 30 V
ans. b
28. The torque of a motor is
a) force is N-m acting on the rotor.
b) the product of tangential force on the motor and its radius.
c) the electrical power in kW.
d) the power given to load being driven by the motor
ans. b
29. The armature current drawn by any d.c. motor is proportional to
a) the voltage applied to the motor.
b) the torque required .
c) the flux required in the motor.
d) the speed of the motor.
ans.
30. The output power of any electrical motor is taken from
a) the armature
b) the coupling mounted on the shaft
c) the conductors.
d) the poles.
ans. b
