Magnetism and electromagnetism

Question 1

What is an induced magnet?

Answer 1

It is an object that BECOMES a magnet when it is placed in a MAGNETIC FIELD.

Question 2

What is a permanent magnet?

Answer 2

A magnet that produces its OWN MAGNETIC FIELD.

Question 3

Name 4 types of magnetic material.

Answer 3

1. iron
2. steel
3. cobalt
4. nickel

(These can be made into a PERMANENT MAGNET or an INDUCED MAGNET).

Question 4

Where is the magnetic field strongest in a magnet?

Answer 4

At the POLES.

Question 5

How can the direction of a magnetic field be found?

Answer 5

Using a COMPASS.

Question 6

How can u plot the magnetic field of a magnet? [6]

Answer 6

• Place the COMPASS near the NORTH pole of the bar magnet. - Then draw a CROSS at the NORTH pole of the compass. - MOVE THE COMPASS so the SOUTH pole of the compass is ON THE CROSS. - Again draw another CROSS at the NORTH pole - Continue until plotted a complete MAGNETIC FIELD LINE.

Question 7

What direction does the magnetic field line always run from?

Answer 7

The NORTH POLE to the SOUTH POLE.

Question 8

What causes the Earth’s magnetic field?

Answer 8

The movement of liquid, magnetic iron in the Earth’s core.

Question 9

What happens when a current flows through a conducting wire?

Answer 9

A MAGNETIC FIELD is produced around the wire.

Question 10

What is a solenoid?

Answer 10

A COIL OF WIRE used to increase the strength of the magnetic field.

Question 11

What 3 ways are there to increase the magnetic field produced by a solenoid?

Answer 11

• Increasing the CURRENT. - Increasing the number of COILS of the WIRE. - Place a piece of IRON inside the solenoid (IRON CORE).

Question 12

What is a solenoid containing an iron core called?

Answer 12

An ELECTROMAGNET.

Question 13

What 2 key uses are there of electromagnets?

Answer 13

1. Can CHANGE the strength of the MAGNETIC FIELD.
2. Can be turned ON and OFF.

Question 14

What is meant by the motor effect?

Answer 14

When a wire carrying an electric current is placed into a magnetic field and experiences a FORCE.

Question 15

What is meant by the magnetic flux density?

Answer 15

It is a measure of the STRENGTH of the magnetic field.

Question 16

How would you determine the direction of the force? (carrying on from motor effect)

Answer 16

Using Fleming’s left hand rule.

Question 17

What does your thumb, first and second finger represent in Fleming’s left hand rule?

Answer 17

• Thumb - motion (the FORCE)
• First finger - magnetic field (N to S).
• Second finger - current (+ to -).

Question 18

What will happen to the conductor when it is parallel to the magnetic field? (carrying on from motor effect)

Answer 18

It will NOT EXPERIENCE A FORCE.

Question 19

Name 1 important use of the motor effect.

Answer 19

Electric motors.

Question 20

What device do we use to switch the direction of the current when the loop passes 90°? (electric motor)

Answer 20

SPLIT-RING COMMUTATOR.

Question 21

What does the split-ring commutator do and what does this allow the motor to do?

Answer 21

Switches the DIRECTION OF THE CURRENT to KEEP ROTATING IN THE SAME DIRECTION.