CP10

Question 1

Why is a bar magnet a permanent magnet?

Answer 1

Because it is always magnetic.

Question 2

What is a permanent magnet?

Answer 2

A magnet that always stays magnetic.

Question 3

What is a magnetic field?

Answer 3

The space around a magnet where it can attract magnetic material.

Question 4

What poles attract to each other when you put two magnets together?

Answer 4

The north pole of one magnet will attract to the south pole of the other magnet and vice versa. Opposites attract.

Question 5

What is an induced magnet?

Answer 5

A piece of material that becomes a magnet because it is in the magnetic field of another magnet.

Question 6

How can the shape of a magnetic field be found?

Answer 6

By using plotting compasses.

Question 7

What is Earths magnetic field similar in shape to?

Answer 7

The shape of the magnetic field of a bar magnet.

Question 8

What does a current flowing through a wire cause?

Answer 8

A magnetic field.

Question 9

What does the direction of the magnetic field depend on?

Answer 9

The direction of the magnetic field depends on the direction of the current. If the current changes direction, so does the direction of the magnetic field.

Question 10

How can you use your thumb to determine the direction of the magnetic field?

Answer 10

If you point your right thumb in the direction of the current, the magnetic field goes in the direction which your fingers are pointing.

Question 11

What does the strength of the magnetic field depend on?

Answer 11

It depends on the size of the current. The higher the current, the stronger the field.

Question 12

How does the strength of magnetic field vary by distance?

Answer 12

The magnetic field is strongest closer to the wire and gets weaker with increasing distance.

Question 13

How does magnetic field around a wire look like?

Answer 13

It looks like multiple circles around the wire.

Question 14

What is an electromagnet?

Answer 14

A magnet made using a coil of wire with electricity flowing through it.

Question 15

What is a coil of wire with a current flowing through it?

Answer 15

A coil of wire with a current flowing through it is an electromagnet.

Question 16

How can the magnetic field of an electromagnet be made stronger?

Answer 16

By putting a piece of iron (an iron core) inside the coil. This iron becomes a temporary magnet - its only magnetic while the field from the electromagnet is affecting it.

Question 17

What is a ‘motor effect’?

Answer 17

The force experienced by a wire carrying a current that is placed in a magnetic field.

Question 18

What is the force that a wire experiences near a magnetic field?

Answer 18

This force occurs because the current in the wire creates a magnetic field around the wire and this interacts with the magnetic field between the magnets. The force is experienced as long as the wire is not in the same direction as the magnetic field.

Question 19

What is Flemings left hand rule?

Answer 19

A way of remembering the direction of the force when a current flows in a magnetic field.

Question 20

What directions are each fingers in Flemings left hand rule?

Answer 20

• The thumb points up
• The index finger points forward
• The middle finger points right

Question 21

What do each finger represent in Flemings left hand rule?

Answer 21

• Thumb = Force(F)
• Index Finger = Magnetic field(B)
• Middle Finger = Current(I)

Question 22

What unit is magnetic flux density measured in?

Answer 22

Newtons per ampere metre(N/Am) but it is also called Tesla(T)

Question 23

What is the formula for the equation involving ‘force on conductor carrying current at right angles to magnetic field’?

Answer 23

Force(N) = Magnetic flux density(N/Am) x Current(A) x Length(M)

Question 24

What is the symbol equation for the equation involving ‘force on conductor carrying current at right angles to magnetic field’?

Answer 24

F = B x I x L (F=Force, B=Magnetic flux density, I=Current, L=Length)