Electrodynamics

Question 1

Energy conversion in generator and motor

Answer 1

Generator: Mechanical kinetic energy to electrical potential energy

Motor: Electrical potential energy to mechanical kinetic energy

Question 2

Purpose of slip rings

Answer 2

• Establish contact between coil and external circuit

- Create alternating current (AC) in external circuit

Question 3

Difference between a DC and an AC generator

Answer 3

• AC uses slip rings, DC uses split ring commutator

- AC current changes direction in external circuit

Question 4

Purpose of split rings or commutator in DC generator

Answer 4

• Maintain contact between coil and circuit

- Alternate current flow into the same side of external circuit to give direct current

Question 5

3 Uses of AC generators

Answer 5

• In electrical power plants, and diesel generators, to convert kinetic energy into electric energy
• In cars to recharge the battery while the car is being driven
• In moving coil microphones. Sound waves makes a coil move. As the coil moves in a magnetic field, a current is induced an this is varying current can be amplifies and fed to a loudspeaker.

Question 6

What is a commutator

Answer 6

A metal ring that has been split into two halves.

Question 7

Electric field

Answer 7

A region of space in which an electric charge exp a force

Question 8

Electric field at a point

Answer 8

Electrostatic force experienced per unit positive charge placed at that point