P15 - Electromagnetism

Question 1

What is a magnetic field?

Answer 1

A region where other magnets or magnetic materials experience a on-contact force.

Question 2

Give three magnetic materials.

Answer 2

• Iron
• Steel
• Nickel
• Cobalt

Question 3

In what direction do magnetic field lines point?

Answer 3

Always from North to South.

Question 4

Describe how you could use a compass to show the direction of a bar magnet’s magnetic field lines.

Answer 4

=> Compass contains tiny bar magnet
=> Move the compass around a bar magnet on a piece of paper and trace its position
=> The north pole of the magnet in the compass points along the field line towards the south pole of the bar magnet

Question 5

Describe the behaviour of a compass that is far away from a magnet.

Answer 5

=> Always point North
=> Because Earth generates own magnetic field
=> This shows that the core of the Earth must me magnetic

Question 6

True or false? The force between a magnet and a magnetic material is always repulsive.

Answer 6

• False

- It always attractive

Question 7

What happens to an induced magnet when it is moved far away from a permanent magnet?

Answer 7

Induced magnet quickly loses its magnetism and stops producing a magnetic field.

Question 8

Describe the magnetic field around a current-carrying wire.

Answer 8

The field is made of concentric circles (one inside the other) perpendicular to the wire, with the wire in the centre.

Question 9

Why does adding more turns to a solenoid increase the strength of its magnetic field?

Answer 9

(A solenoid is a coil of wire)

• Field lines around each loop of wire line up with each other
• Results in lots of field lines pointing in the same direction that are very close to each other.
• Closer the field lines are, stronger the field is.

Question 10

Describe an electromagnet and give one example of where it could be used.

Answer 10

• A solenoid with an iron core is called an electromagnet
• The magnetic field can be switched on and off with an electric current)
• Cranes in scrap yards
• Can be used as switches within other circuits

Question 11

How do you use the Right-Hand Thumb Rule?

Answer 11

• Using your right hand (obviously)
• Point thumb in direction of current
• Curl fingers into palm
• Direction of fingers in the direction of the magnetic field.