Electrical Machines (Part-10)

What is the primary function of a generator?

A To step down voltage
B To step up voltage
C To convert mechanical energy into electrical energy
D To convert electrical energy into mechanical energy

Which type of current is supplied to an induction motor?

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

What happens to the efficiency of a motor at light load?

A It decreases
B It increases
C It remains constant
D It becomes zero

What is the primary cause of humming noise in a transformer?

A Copper losses
B Magnetostriction in the core
C Mechanical vibrations in windings
D Eddy current losses

What is the primary function of a cooling fan in large electrical machines?

A To step up the voltage
B To dissipate heat generated by losses
C To reduce the magnetic field strength
D To increase current

Which component in a DC motor is responsible for reversing current direction?

A Brushes
B Commutator
C Field winding
D Stator

What is the primary cause of eddy current losses in electrical machines?

A Friction in moving parts
B Circulating currents in the core
C Resistance in the windings
D Overloading

What is the purpose of a step-down transformer?

A To reduce voltage levels
B To step up current
C To step up voltage
D To increase frequency

What type of motor is most commonly used in electric traction systems?

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

What is the main loss reduced by laminating the core of electrical machines?

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

What happens to the efficiency of a motor at light load?

A It increases
B It decreases
C It remains constant
D It becomes zero

What is the primary cause of eddy current losses in electrical machines?

A Friction in moving parts
B Circulating currents in the core
C Resistance in the windings
D Overloading

What is the purpose of a step-down transformer?

A To reduce voltage levels
B To step up current
C To step up voltage
D To increase frequency

What type of motor is most commonly used in electric traction systems?

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

What is the main loss reduced by laminating the core of electrical machines?

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

What is the main advantage of using a squirrel cage rotor in an induction motor?

A Simple construction and robustness
B High starting torque
C High efficiency at no-load
D Better power factor

Which motor is most suitable for precision control in robotics?

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

What is the function of a damping winding in synchronous machines?

A To suppress oscillations and stabilize the rotor
B To increase rotor resistance
C To increase torque
D To reduce slip

What is the role of insulation in electrical machines?

A To prevent electrical leakage and short circuits
B To reduce friction
C To generate power
D To enhance magnetic flux

What happens to the slip in an induction motor when the load increases?

A Slip increases
B Slip decreases
C Slip remains constant
D Slip becomes zero