(6.2-6.7) Magnetism

What is the law of magnetism?

When two magnets are held close together, there will be either a repulsive or attractive force.

Like poles…

repel.

Opposite poles…

attract

What causes the attraction/repulsion between magnets?

magnetic force

What are the properties of magnetically soft materials?

• easy to magnetise

• easily lose their magnetism

• used for electromagnets

What are the properties of magnetically hard materials?

• difficult to magnetise

• do not easily lose their magnetism

• used to make permanent magnets

What is a magnetic field?

The region around a magnet where a force acts on another magnet/magnetic material

What are magnetic field lines? How are they drawn?

lines used to represent the strength and direction of a magnetic field

• direction with arrows= always N→S

• magnitude with spacing

  • close together = stronger

  • far apart = weaker

• they can never touch/cross

Where does a uniform magnetic field form?

Only in the gap between 2 opposite poles

• same strength and direction at all points

How can you tell whether an object is a magnet?

If it is repelled by a known magnet, it is.

If it is only attracted, it is not.

What is induced magnetism? Mention the characteristics.

An object can be temporarily turned into a magnet

by placing it in a magnetic field.

The end closest to the magnet will have the opposite pole to the closest magnet pole.

Describe how to investigate the magnetic field pattern for a permanent bar magnet.

1. Place the magnets on a piece of paper.

2. Draw a dot at a corner.

3. Place compass next to the dot. Draw the next dot on the other side of the compass needle.

4. Move compass so it’s end is in front of the new dot and carry on.

5. Do this for all the corners and join the dots down each line.