GCSE-Electromagnetism

Question 1

Fleming’s left hand rule predicts the direction of the force on an electric current flowing in a …?

Answer 1

magnetic field

Question 2

In Fleming’s left hand rule the current, field lines and force are all …?… to each other

Answer 2

perpendicular

Question 3

In Fleming’s left hand rule the first finger represents the direction of the …?

Answer 3

magnetic field

Question 4

In Fleming’s left hand rule the second finger represents the direction of the …?

Answer 4

current

Question 5

In Fleming’s left hand rule the thumb represents the direction of the …?

Answer 5

force

Question 6

Turns-ratio equation for a transformer

Answer 6

Vs/Vp = ns/np

Question 7

Power equation for a transformer

Answer 7

VpIp = VsIs

Question 8

The magnetic field produced by a current flowing through a coil of wire has the same shape as the field caused by a …?… …?…

Answer 8

bar magnet

Question 9

If the current flow in a coil is clockwise as seen from one end of the coil, then that end is a …?… pole

Answer 9

South

Question 10

If the number of turns on a current-carrying coil is increased, then the strength of its magnetic field …?

Answer 10

increases

Question 11

If the current flowing through a coil is decreased, then the strength of its magnetic field …?

Answer 11

decreases

Question 12

The strength of the magnetic field caused by a current-carrying coil will increase if it is given a core made of …?

Answer 12

iron

Question 13

If a conductor and/or magnet is moved so that the conductor cuts across magnetic field lines, then …?… …?… is induced in the conductor

Answer 13

electric current

Question 14

If the current flowing through a coil is changed, then electric current is …?… in a nearby second coil.

Answer 14

induced

Question 15

Step-up and step-down transformers help to …?… power losses in power lines.

Answer 15

reduce

Question 16

Equation for the force F on a straight conductor of length L carrying a steady current I at right angles to a magnetic field of strength B

Answer 16

F = BIL

Question 17

When a bar magnet is plunged into a coil, a …?… flows in the coil.

Answer 17

current

Question 18

The current induced in a coil by plunging a bar magnet into it …?… if the magnet is moved more slowly.

Answer 18

decreases

Question 19

The current induced in a coil by plunging a bar magnet into it increases if a …?… magnet is used.

Answer 19

stronger

Question 20

The current induced in a coil by plunging a bar magnet into it is…?… for a coil with fewer turns.

Answer 20

smaller

Question 21

What happens when a magnet which was plunged into a coil is then removed again at the same speed?

Answer 21

The current now induced is equal to the original but in the opposite direction.

Question 22

What happens when a bar magnet which was plunged into a coil is plunged in again at the same speed but with the opposite pole facing the coil?

Answer 22

The current now induced is equal to the original but in the opposite direction.

Question 23

The current induced in a coil by plunging a bar magnet into it stops when …?

Answer 23

the magnet is totally inside the coil.

Question 24

What happens when a magnet which was plunged into a coil sits stationary inside the coil?

Answer 24

No current is induced.

Question 25

What happens when a bar magnet is rotated close to a coil of wire?

Answer 25

An alternating current is induced in the coil.

Question 26

When the current is switched on in one coil, what happens in a nearby coil?

Answer 26

A current is induced which flows only while the first current is rising to its final steady value.

Question 27

When a steady current is switched off in one coil, what happens in a nearby coil?

Answer 27

A large current is induced in the opposite direction to that when the steady current was switched on. The induced current flows only while the first current is falling to zero.

Question 28

A coil of wire rotating between the poles of a magnet is the simplest form of ...?

Answer 28

a.c. generator.

Question 29

Do transformers work with a.c. or d.c.?

Answer 29

a.c.

Question 30

What kind of transformer has more turns on the secondary coil than the primary coil?

Answer 30

Step-up transformer

Question 31

For what kind of transformer is the output voltage less than the input voltage?

Answer 31

Step-down transformer

Question 32

What does the soft-iron core in a transformer do?

Answer 32

It channels the magnetic field lines from the primary coil through the secondary coil.

Question 33

What is the difference between a.c. and d.c.?

Answer 33

d. c. is constant in size and direction. | a. c. continually changes in size and reverses in direction.