Electrical Machines (Part-1)

What is the primary function of a DC motor?

A Store energy
B Convert electrical energy to mechanical energy
C Generate power
D Control speed

What type of machine is a synchronous motor?

A Brushless machine
B DC machine
C AC machine
D Induction machine

In a DC motor, what component reverses the direction of current flow in the armature?

A Commutator
B Field windings
C Stator
D Rotor

What is the primary cause of efficiency losses in electrical machines?

A Electrical losses
B Magnetic losses
C Mechanical losses
D Core losses

What does “slip” refer to in an induction motor?

A The torque produced by the motor
B The voltage difference across the motor
C The speed difference between rotor and stator
D The resistance of the motor

Which of the following motors is typically used in robotics for precise control?

A Synchronous motor
B Stepper motor
C Induction motor
D DC motor

What is the function of field windings in a DC motor?

A To generate a magnetic field
B To support the rotor
C To reduce losses
D To control the speed of the motor

Which of the following is not a method of starting a squirrel-cage induction motor?

A Direct-on-line starting
B Star-delta starting
C Commutator starting
D Autotransformer starting

In an induction motor, what is the purpose of the rotor?

A To generate a magnetic field
B To control the speed
C To supply power to the stator
D To provide mechanical energy

What type of loss is minimized by using laminated cores in electrical machines?

A Copper losses
B Hysteresis losses
C Eddy current losses
D Mechanical losses

In a synchronous motor, what causes the motor to run at synchronous speed?

A The supply frequency
B The load torque
C The rotor’s speed
D The field winding’s strength

Which of the following is a characteristic of a permanent magnet motor?

A Large size
B High torque at low speeds
C High efficiency
D Requires external excitation

What is the main purpose of the commutation in a DC motor?

A To reduce torque ripple
B To increase motor speed
C To prevent overheating
D To reverse current direction

What does “voltage regulation” refer to in electrical machines?

A The ability to maintain constant voltage under varying load conditions
B The rate of change in current
C The ability to reduce heat generation
D The ability to maintain constant speed

Which loss is mainly due to the resistance of the windings in a motor?

A Mechanical loss
B Copper loss
C Core loss
D Eddy current loss