1. The direction of rotation of a DC motor can be determined by:
2. What will happen if DC shunt motor is connected across AC supply?
- Will run at normal speed
- Will not run
- Will Run at a lower speed
- Burn due to heat produced in the field winding
3. Which of the following motor is used where high starting torque and wide speed range control is required?
- All motors
- Induction motor
- Synchronous motor
- DC motor
4. The function of a commutator in a D.C. machine is to _____
- Prevent sparking
- Reduce iron losses
- Reduce friction
- Change alternating voltage to direct voltage
5. What will happen if the back emf of a DC motor vanishes suddenly?
- The motor will stop
- The motor will continue to run
- The armature may burn
- The motor will run noisy
6. The armature voltage control of DC motor will provide _______
- Constant power drive
- Constant voltage drive
- Constant current drive
- Constant torque drive
7. A 4-pole, lap-connected, separately excited dc motor is drawing a steady current of 40 A running at 600 RPM. What is the frequency of DC motor?
- 50 Hz
- 25 Hz
- 20 Hz
- 10 Hz
8. What will happen when the speed of the DC motor increases?
- Back emf increases but line current falls.
- Back emf falls and line current increase.
- Both back emf as well as line current increase.
- Both back emf as well as line current fall.
9. As there is no back emf at the instant of starting a DC motor, in order to prevent a heavy armature current from flowing through the armature circuit ______
- Series resistance is connected with armature
- Parallel resistance is connected to the armature
- Armature is temporarily open circuited
- High-value resistor is connected across the field winding
10. The torque of a D. C. Shunt Motor is directly proportional to
- Armature current
- Field current
- Impressed voltage
- Number of poles