Electrical Machines (Part-12)

What is the primary function of an alternator?

A To convert DC to AC
B To generate AC power
C To step up voltage
D To convert mechanical energy into heat

Why is a centrifugal switch used in a single-phase motor?

A To disconnect the starting winding after reaching sufficient speed
B To control the direction of rotation
C To improve power factor
D To regulate voltage

What is the main use of a transformer?

A To step up or step down voltage levels
B To convert AC to DC
C To convert mechanical energy into electrical energy
D To store electrical energy

Which type of current is induced in the secondary winding of a transformer?

A Alternating current (AC)
B Direct current (DC)
C Pulsating current
D Constant current

What does the term “slip” represent in an induction motor?

A Efficiency of the motor
B The difference between synchronous speed and rotor speed
C Voltage regulation
D Rotor resistance

What is the primary role of field winding in a DC machine?

A To carry load current
B To produce the magnetic field
C To reduce resistance
D To improve efficiency

Which type of motor is used for elevators?

A Induction motor
B Universal motor
C Stepper motor
D Brushless DC motor

What type of loss occurs due to repeated magnetization and demagnetization of the core?

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

What is the primary purpose of a step-down transformer?

A To reduce voltage levels
B To step up voltage
C To convert AC to DC
D To store energy

What is the primary function of rotor bars in an induction motor?

A To carry induced current
B To step up voltage
C To reduce slip
D To increase torque

What does the term “core loss” refer to in an electrical machine?

A Losses due to hysteresis and eddy currents in the core material
B Losses due to resistance in the windings
C Losses caused by friction in moving parts
D Losses due to heat generated in the motor

Which type of motor is commonly used for precision movement in robotics?

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

What is the primary advantage of a brushless DC motor over a brushed DC motor?

A Longer lifespan due to the absence of brushes
B Higher torque at low speeds
C Lower cost of construction
D Higher power factor

What type of transformer is used for electrical power distribution?

A Isolation transformer
B Step-down transformer
C Step-up transformer
D Autotransformer

What is the primary function of rotor bars in an induction motor?

A To carry induced current
B To step up voltage
C To reduce slip
D To increase torque

What is “core loss” in an electrical machine?

A Losses due to hysteresis and eddy currents in the core material
B Losses caused by friction in moving parts
C Losses due to resistance in windings
D Losses due to heat generated in the machine

Which type of motor is commonly used for precision movement in robotics?

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

What is the primary advantage of a brushless DC motor over a brushed DC motor?

A Longer lifespan due to the absence of brushes
B Higher torque at low speeds
C Lower cost of construction
D Higher power factor

What type of transformer is used for electrical power distribution?

A Isolation transformer
B Step-down transformer
C Step-up transformer
D Autotransformer

What is the primary function of rotor bars in an induction motor?

A To carry induced current
B To step up voltage
C To reduce slip
D To increase torque