CH4

Question 1

Definition of catapult field

Answer 1

Resultant magnetic field produced by the interaction of magnetic field of the current-carrying conductor and magnetic field of the permanent magnet

Question 2

Factors affecting magnitude of force on a current-carrying conductor in a Magnetic field

Answer 2

Current
Magnetic field strength

Question 3

Function of a commutator in a motor

Answer 3

Change direction of current in the coil every half turn

Question 4

Additional factor that affect speed of motor rotation

Answer 4

Number of turns of the coil

Question 5

Function of carbon brush

Answer 5

conduct electric current into the coil

Question 6

4 Characteristics of brushless motor

Answer 6

Stationary coil & rotating magnet
No Carbon brush; No friction between brush and commutator
No Sparking at commutator
Soft operational sound

Question 7

4 Characteristics of Brushed Motor

Answer 7

Stationary Magnet, rotating coil
Carbon brush wears out due to friction
Sparking at commutator
Louder operational sound

Question 8

Definition of electromagnetic induction

Answer 8

Production of an induced electromotive force in a conductor when there is in a relative motion between conductor and magnetic field or in a changing magnetic field

Question 9

Explain how an induced current is produced

Answer 9

Magnetic field line is cut by (conductor)
Electromotive force is induced into the wire due to electromagnetic induction
Induced current is produced in (conductor)

Question 10

Factors affecting magnitude of induced e.m.f in an electromagnetic induction

Answer 10

Speed of relative motion
strength of magnetic field
Number of turns of a solenoid coil

Question 11

Purpose of circular permanent magnet in an electromagnet generator / motor

Answer 11

Produce a radial magnetic field

Question 12

Purpose of soft iron core of an electromagnet generator // motor

Answer 12

concentrate magnetic field lines

Question 13

Lenz Law

Answer 13

Induced current is always in the direction that opposes the change of magnetic flux that causes it

Question 14

Working principle of a transformer (4m)

Answer 14

AC power supply provide Alternating current
Alternating current produced magnetic field that changes in direction and magnitude
Soft iron core link magnetic flux from primer coil to secondary coil
Alternating voltage is induced in secondary coil due to changing magnetic field

Question 15

Definition of ideal transformer

Answer 15

A Transformer does not experience any loss of energy