P7

Question 1

Magnetic field

Answer 1

The area where a force acts on another magnet or magnetic material

Question 2

Poles

Answer 2

The place on a magnet where the magnetic force is the strongest

Question 3

Like poles

Answer 3

repel

Question 4

Unlike poles

Answer 4

attract

Question 5

Permanent magnet

Answer 5

Produces its own magnetic field

Question 6

Induced magnet

Answer 6

A material that becomes magnetic when placed in a magnetic field

Question 7

Magnetic metals

Answer 7

iron, cobalt, nickel and steel

Question 8

The force between a magnet and a magnetic material

Answer 8

always attraction

Question 9

Direction of magnetic field lines

Answer 9

North to south

Question 10

Magnetic compass

Answer 10

Works by using the earths magnetic field facing the bar magnet towards the north

Question 11

How to plot magnetic field patterns

Answer 11

Place a magnet on an A4 paper, move a compass equal distances and plot where the pin faces

Question 12

How is a magnetic field produced around a wire?

Answer 12

A current is induced.(The stronger the current the syringe the magnetic field)

Question 13

How to increase the strength of a magnetic field through a wire

Answer 13

Coil it making it a solenoid

Question 14

Magnetic field in a solenoid

Answer 14

Strong and uniform

Question 15

Electromagnetic

Answer 15

a solenoid with a soft iron core

Question 16

Magnetic field around a solenoid

Answer 16

A similar shape to a bar magnet

Question 17

Fleming left had rule

Answer 17

Thumb = force
Index finger = magnetic field
Middle finger = Current direction

Question 18

Electric motor

Answer 18

a coil of wire carrying a current will have a rotating magnetic field( right hand thumb rule)

Question 19

Alternator

Answer 19

produces AC

Question 20

Dynamo

Answer 20

Produces DC

Question 21

Magnetic field of an induced current

Answer 21

opposes the original change

Question 22

Factors affecting the size of the induced potential difference/current

Answer 22

Speed of the magnets movement or size of the magnetic field

Question 23

How to reverse the direction of an induced current

Answer 23

change the direction of the magnets movement or magnetic field

Question 24

Use of the generation affect

Answer 24

In dynamos or alternators

Question 25

Microphones

Answer 25

Use the generator effect to convert the pressure variations in sound waves to variations in electrical circuit’s

Question 26

Transformer

Answer 26

Has a primary and secondary coil to step up or down the current and P.D respectively

Question 27

Why is an iron core used in transformers

Answer 27

it is easily magnetised

Question 28

What determines the ratio of P.D over transformer coils

Answer 28

The ratio of turns on each coil

Question 29

Step-up transformer

Answer 29

Vs > Vp

Question 30

Step-down transformer

Answer 30

Vs < Vp

Question 31

Vp and Vs

Answer 31

Primary voltage and the secondary voltage

Question 32

np and ns

Answer 32

Primary number of coils and secondary number of coils

Question 33

100% efficient transformer

Answer 33

Electrical input is the same as the electrical output

Question 34

How a transformer works

Answer 34

- AC flows through the primary coil - This AC induces and alternating magnetic field - The alternating magnetic field in the iron core induces alternating PD in the secondary coil - AC flows through the secondary coil

Question 35

Magnetic flux density

Answer 35

The strength of a magnetic field measured in Tesla (T)

Question 36

Solenoid

Answer 36

long straight coil of wire