Topic 10 & 11 - Magnetism and the Motor Effect and Electromagnetic Induction

Question 1

1 What are the two ends of a bar magnet called?

Answer 1

north-seeking pole and south-seeking pole, or just north pole and south pole

Question 2

2 Name two magnetic materials.

Answer 2

any two from iron, cobalt, nickel, steel

Question 3

3 What happens if you arrange two magnets with their north poles close to each other?

Answer 3

They repel each other.

Question 4

4 How can you arrange two magnets so they attract each other?

Answer 4

put opposite poles close to each other/put a north pole near a south pole

Question 5

5 What is a magnetic field?

Answer 5

the space around a magnet which affects magnetic materials

Question 6

6 How can you find the shape of a magnetic field?

Answer 6

use iron filings or plotting compasses

Question 7

7 Name two electrical devices that use magnets.

Answer 7

any two from motors, loudspeakers, generators

Question 8

8 Why do compasses point north?

Answer 8

The Earth has a magnetic field.

Question 9

9 Describe the shape of the Earth?s magnetic field.

Answer 9

similar to the field of a bar magnet

Question 10

10 Why are compass needles weighted at one end?

Answer 10

In most places the Earth’s magnetic field is not parallel to the surface.

Question 11

11 Which part of the Earth is responsible for the Earth?s magnetic field?

Answer 11

outer core

Question 12

12 What is the difference between the Earth?s north magnetic pole and its North Pole?

Answer 12

The Earth spins around an axis through the North Pole; the north magnetic pole is where compasses point to.

Question 13

13 What is an induced magnet?

Answer 13

something that is a magnet only because it is in the magnetic field of another magnet

Question 14

14 Name two materials that an induced magnet could be made from.

Answer 14

any two from iron, cobalt, nickel, steel

Question 15

15 You are using plotting compasses to find the shape of the magnetic field of a bar magnet. Which way does the needle point?

Answer 15

away from the north pole/towards the south pole

Question 16

16 How does a magnetic field diagram show where the field is strongest?

Answer 16

strongest where the lines are closest together

Question 17

17 What is a uniform magnetic field?

Answer 17

a field with the same strength and direction everywhere

Question 18

18 How can you produce a uniform magnetic field?

Answer 18

using two flat magnets

Question 19

19 What is the shape of the magnetic field around a wire with a current flowing through it?

Answer 19

circular around the wire

Question 20

20 What is an electromagnet?

Answer 20

a magnet made when current flows through a coil of wire

Question 21

21 How can you create a magnetic field around a wire?

Answer 21

pass a current through it

Question 22

22 Where is the magnetic field of a wire strongest?

Answer 22

close to the wire

Question 23

23 How can you increase the strength of the field around a wire?

Answer 23

increase the current

Question 24

24 How can you change the direction of the field around a wire?

Answer 24

change the direction of the current

Question 25

25 What is a solenoid?

Answer 25

a coil of wire with a current flowing through it/another name for an electromagnet

Question 26

26 Why is an electromagnet called a temporary magnet?

Answer 26

It is only magnetic when a current is flowing.

Question 27

27 Describe the magnetic field inside a solenoid.

Answer 27

uniform, along the centre of the coil

Question 28

28 Why is the magnetic field of a solenoid stronger inside the coil than outside it?

Answer 28

The fields from the two halves of the coil reinforce each other in the middle and partially cancel each other out outside it .

Question 29

29 Describe the magnetic field between two flat magnets.

Answer 29

uniform, has the same strength and direction everywhere

Question 30

30 What is the motor effect?

Answer 30

a force produced when a current flows in a magnetic field

Question 31

31 How can you make a magnetic field around a wire?

Answer 31

pass a current through the wire

Question 32

32 Where is the magnetic field of a wire strongest?

Answer 32

close to the wire

Question 33

33 How can you increase the strength of the field around a wire?

Answer 33

increase the current

Question 34

34 What is a solenoid?

Answer 34

a coil of wire with a current flowing through it/another name for an electromagnet

Question 35

35 Why is an electromagnet called a temporary magnet?

Answer 35

it is only magnetic when a current is flowing

Question 36

36 Give two ways of increasing the strength of the motor effect

Answer 36

increase the current, use a stronger magnetic field

Question 37

37 What does Fleming?s left-hand rule help you to work out?

Answer 37

the direction of the force produced when a current flows in a magnetic field

Question 38

38 What does magnetic flux density measure?

Answer 38

strength of a magnetic field

Question 39

39 What are the units for magnetic flux density?

Answer 39

tesla, or newtons/amp metre

Question 40

40 What is a transformer?

Answer 40

a device for changing the potential difference of an electricity supply

Question 41

41 What does a transformer do?

Answer 41

changes the potential difference of an electricity supply

Question 42

42 What are the two sets of coils in a transformer called?

Answer 42

primary and secondary coils

Question 43

43 What are the coils in a transformer wound onto?

Answer 43

iron core

Question 44

44 What does potential difference measure?

Answer 44

energy transferred by each coulomb of charge

Question 45

45 What is the equation for calculating electrical power?

Answer 45

power = current x potential difference

Question 46

46 What are the units for electrical power?

Answer 46

watts

Question 47

47 100 W of power are transferred to a transformer via the primary coil. How much power is transferred away from the transformer?

Answer 47

100 W

Question 48

48 What is the national grid?

Answer 48

the wires and transformers that send electricity around the country

Question 49

49 What is a transmission line?

Answer 49

the wires on pylons or underground that transfer electricity

Question 50

50 What is the difference between a step-up and a step-down transformer?

Answer 50

one increases the voltage and the other decreases it