DC Motor

Question 1

What is the rotor of a DC motor generally made from?

Answer 1

Thin strips of steel

Question 2

What does Maxwell’s Right Hand Grip Rule indicate?

Answer 2

The direction of the magnetic field around a conductor.

Question 3

What will lines of magnetic flux never do?

Answer 3

Cross over

Question 4

Using Fleming’s Left Hand Rule, what does each digit indicate?

Answer 4

Thumb=motion, first finger=field, second finger=current.

Question 5

What is Back EMF?

Answer 5

Opposite in polarity to the EMF applied.

Question 6

The amount of torque produced by a motor is dependent upon what two things?

Answer 6

Strength of the magnetic field and magnitude of the armature current

Question 7

List the 3 classifications of DC motors

Answer 7

Series, Shunt and compound.

Question 8

What must the carbon brushes be fixed in the same position as? And why?

Answer 8

There is no back EMF in the coil

Question 9

Describe armature reaction

Answer 9

The armature field will distort the field winding magnetic field.

Question 10

What are inter-poles, where are they fitted and what do they do?

Answer 10

Prevents sparks and compensate for armature reaction.