Magnetism and permanent and induced magnets

soft magnetic materials

materials thatlose their induced magnetism quickly

hard magnetic materials

materials that lose their induced magnetism slowly even after the magnetic field has been removed they retain their magnetism for some time

What is a magnet?

A magnet is an object that produces a magnetic field and can attract or repel certain materials

Which materials are magnetic?

Only iron, nickel, cobalt, and some of their alloys are magnetic.

What is a magnetic field?

A magnetic field is the region around a magnet where magnetic forces act on other materials or magnets.

What do magnetic field lines show?

They show the direction and strength of the magnetic field. Lines closer together indicate a stronger field.

What is the direction of a magnetic field?

Magnetic field lines always point from the north pole to the south pole outside the magnet.

What are permanent magnets?

Permanent magnets always produce a magnetic field and cannot be easily demagnetized (e.g., bar magnets, fridge magnets).

What are induced magnets?

Induced magnets are materials that become temporarily magnetized when placed in a magnetic field.

What happens to an induced magnet when removed from a magnetic field?

It loses its magnetism.

What happens when two like poles or opposite poles are brought close?

Like poles (N-N or S-S) repel

• Opposite poles (N-S) attract

Why does a compass point north?

A compass needle aligns with the Earth's magnetic field, as the Earth has a magnetic north and south pole.

how are the poles like in a magnetic material

the poles are all aligned in the same direction

how are the poles like in a non magnetic material

the poles aren’t aligned so then the magnetic fields cancel each other out and the substance is non magnetic

the force between a magnetic material and a magnet is always ______ a _______ force is only ever experienced between two magnets

attractive, repulsive\

what happens when a magnetic material becomes magnetised

the poles shift their alignment in response so if it’s exposed to the north pole of the magnet the magnetic material will have an induced south pole

where will a uniform magnetic field be produced

in the gap between two opposite poles howeevr outside the gap the field won’t be uniform

what is a uniform magnetic field

a field that has the same strength and direction at every point

describe how to plot a magentic field

1. place a magnet on top of a piece of paper and draw a dot at one end of the magnet in the corner

2. place the plotting compass next to the dot and use a pencil to draw a new dot at the other side of the compass needle

3. move the compass so that it points away from the new dot and repeat the process above

4. repeat the process until there is a chain of dots and connect with a smooth curve