QUIZ-2 EM-1

The armature of DC motor is laminated to ____________

• To reduce mass

• To reduce hysteresis loss

• To reduce eddy current loss

• To reduce inductance

When Ea>Vt machine is said to be operating in which of the following mode?

• Depends on the Shaft speed

• Generating

• Motoring

• Inducing

Why starters are required in a DC motor?

• Back emf of these motors is zero initially

• These motors are not self-starting

• These motors have high starting torque

• To restrict armature current as there is no back emf at starting

In a DC shunt motor, speed is related to armature current as _____________

• Directly proportional to the armature current

• Inversely proportional to the armature current

• Proportional to the square of the current

• Independent of armature current

No-load speed of which of the following DC motor will be highest?

• Series motor

• Cumulative compound motor

• Shunt motor

• Differentiate compound motor

What will happen, with the increase in speed of a DC motor?

• Back emf increase 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.

Which part will surely tell that given motor is DC motor and not an AC type?

• Winding

• Shaft

• Commutator

• Stator

Direction of rotation of motor is determined by ____________

• Faraday’s law

• Lenz’s law

• Coulomb’s law

• Fleming’s left-hand rule

The current drawn by the armature of DC motor is directly proportional to

• Torque

• Speed

• The voltage across the terminals

• Cannot be determined

In which of the following case we will get maximum power?

• Ea = 2 x supply voltage

• Ea = supply voltage

• Supply voltage = 2 x Ea

• supply voltage = 4 x Ea