Physics

Question 1

Magnet

Answer 1

A piece of material that is capable of attracting certain metals.

Question 2

Name some uses of magnets

Answer 2

In MRI machines, food processing, inside TVs, Sound speakers and radios, headphones and loudspeakers, generators

Question 3

Permanent magnets

Answer 3

A magnet which remains magnetic without the need for an electric current because of the internal structure of the magnet. They can be used to attract other objects e.g. paperclips made of steel

Question 4

Give some examples of permanent magnets

Answer 4

Paper clips, bar magnet, Horse shoe magnet, Compass, Button magnet

Question 5

Magnetic material

Answer 5

A material which is attracted by a magnet

Question 6

Non-magnetic material

Answer 6

A material which is not attracted by a magnet

Question 7

Give examples of magnetic materials

Answer 7

Iron ,steel, nickel ,cobalt

Question 8

Give examples of non-magnetic material

Answer 8

Wood, cotton, paper, aluminium, tin

Question 9

______ is mostly made of iron

Answer 9

Steel

Question 10

What are strong magnets made out of nowadays?

Answer 10

Neodymium

Question 11

How can we separate different material?

Answer 11

By using a strong magnet that can attract magnetic material and the non-magnetic material will be left behind

Question 12

Magnetic poles

Answer 12

The regions of a permanent magnet where the magnetic strength is strongest

Question 13

Magnetic force

Answer 13

The force of a magnet on another magnet or on a piece of magnetic material

Question 14

What are the magnet rules?

Answer 14

Like poles repel and unlike poles attract

Question 15

How can we magnetise a magnetic material?

Answer 15

• Lay it on the bench
• Using one pole of the magnet, stroke it from one end to the other.
• Stroke it several times, using the same pole.
• Make sure you always stroke it in the same direction

Question 16

Where will the north and south pole of a magnet turn?

Answer 16

The north pole of a magnet will turn to point north and the south pole of a magnet will turn to point south

Question 17

When to unlike poles attract what does that mean?

Answer 17

It can be a magnet or a magnetic material

Question 18

When to like poles repel what does that mean?

Answer 18

They are permanent magnets

Question 19

Magnetic field

Answer 19

A region where there is a force on a magnet or a piece of magnetic material

Question 20

What will happen when a magnetic material is placed in the field of a magnet?

Answer 20

It will be attracted by the magnet

Question 21

How can we show the shape of a magnetic field?

Answer 21

• By using iron fillings to form a line
• Using plotting compasses to show the direction of the field

Question 22

How can we represent a magnetic field?

Answer 22

By drawing magnetic field lines

Question 23

What do magnetic fields show?

Answer 23

• They go from north to south
• The arrows show the direction of the field
• Where the lines are closest together is where the field is the strongest

Question 24

Why do people use a compass?

Answer 24

Because the Earth has a magnetic field that can help us find our way around

Question 25

Where will a compass needle point towards?

Answer 25

Earth's magnetic north pole which is near to the geographical north pole

Question 26

Electromagnet

Answer 26

A coil of wire with an electric current in it that works using electricity and it can be switched on and off

Question 27

How can we construct an electromagnet?

Answer 27

By winding a coil and then connecting the ends of the wire to a battery or power supply

Question 28

Name 2 differences between an electromagnet and a permanent magnet

Answer 28

- An electromagnet uses electricity but a permanent magnet doesn't - An electromagnet can be switched on and off, while a permanent magnet can't.

Question 29

Why can we switch an electromagnet on and off?

Answer 29

Because it's easy to switch electricity

Question 30

How can we make an improved electromagnet?

Answer 30

We can wrap the wire around a magnetic material (e.g iron) called a core so that when the iron becomes magnetised and this makes the magnetic field of the electromagnet stronger

Question 31

Core

Answer 31

A piece of iron inside the coil of an electromagnet to make it stronger

Question 32

Name 3 uses of an electromagnet

Answer 32

- For carrying heavy scarp cars - In electric motors and generations - In doorbells and in electric switches called relays

Question 33

How can we make an electromagnet stronger?

Answer 33

- Make a coil with more turns of wire - Make a bigger electric current flow in the coil of wire by connecting 2 batteries end-to-end

Question 34

Ammeter

Answer 34

A meter used for measuring electric current

Question 35

Amps

Answer 35

The unit in which electric current is measured, symbol A

Question 36

How is the field of an electromagnet like the field of a bar magnet?

Answer 36

- The magnetic field lines come out of one end of the electromagnet (the north pole) - The field lines go round and back into the other end electromagnet (the south pole)

Question 37

What makes the magnetic field in an electromagnet?

Answer 37

The current makes the magnetic field

Question 38

Who is Hans Christian Oersted?

Answer 38

A Danish scientist who thought that there might be a connection between electricity and magnetism in 1820

Question 39

What happened in 1820?

Answer 39

Hans gave a lecture about electric circuits and a compass was nearby. When he switched on the circuit, he noticed the compass needle change directions

Question 40

How does an electromagnet work in terms of it's magnetic field?

Answer 40

The magnetic field around an wire is weak so when we wind the wore into a coil you concentrate the magnetic field into a smaller space making it much stronger

Question 41

What shape are the magnetic fields in an electric current?

Answer 41

Circle

Question 42

Where is the magnetic field the strongest in an electric current?

Answer 42

The field is strongest close to the wire