## Quiz sheet for machine principles

An electric motor operates as a result of the:

A) magnetic effect of an electric current.

B) chemical effect of an electric current.

C) heating effect of an electric current.

D) physiological effect of an electric current.

ANSWER: A

An increase in the load applied to a DC motor will cause the motor speed to ______ and the motor torque to ______ .

A) decrease, increase

B) Decrease, decrease

C) Increase, increase

D) Increase, decrease

ANSWER: A

In a transformer, a changing current in the secondary coil causes a change in the:

A) resistance

B) resistor

C) inductor

D) primary coil

ANSWER: D

In an A.C generator, increasing the number of turns in coil

A) increases the EMF

B) decreases the EMF

C) doesn't effect the EMF

D) removes the EMF

ANSWER: A

In transformer if secondary voltage is more than primary voltage then it is called

A) step up transformer

B) step down transformer

C) inductor

D) resistor

ANSWER: A

In transformer primary coil is connected to

A) AC source

B) DC source

C) resistor

D) inductor

ANSWER: A

Increasing load on a motor will cause it to slow down. This will result in

A) less back emf

B) less torque

C) less current

D) less power

ANSWER: A

The function of the commutator in a DC generator is to:

A) convert the AC generated in the windings to DC when connecting to an external circuit.

B) connect the AC generated in the windings directly to an external circuit.

C) supply an external current to the armature to drive the generator.

D) allow the generator to be converted to a motor.

ANSWER: A

The torque produced in a DC motor is _____ to the armature current and ______ to the main field flux.

A) Proportional, proportional

B) Inversely Proportional, proportional

C) Inversely Proportional, Inversely proportional

D) Proportional, Inversely proportional

ANSWER: A

Transformers are application of

A) mutual induction

B) induction

C) electrostatics

D) mutual charges

ANSWER: A

Last modified: Tuesday, 1 June 2021, 9:23 AM