Physics- magnets and electromagnets

What are the two ends of a permanent magnet called?

North and South poles.

Forces

A push or a pull. repulsion/attraction

Like poles of a magnet (N-N/S-S)

repel each other

Unlike poles of a magnet (S-N/N-S)

Attract each other

repel

to push away

attract

to pull toward

Magnetism

The force of attraction or repulsion of magnetic materials

Electromagnetism

the interaction of electric currents or fields and magnetic fields.

bar magnet

a magnet in the form of a bar with magnetic poles at each end

horseshoe magnet

a type of magnet that has a bend in the middle

magnetic field lines

show the direction of a magnetic field at different points.

What happens if a magnet it cut in half?

It becomes two different magnets

What does the compass indicate in field lines

The lines that run from north to south

Why do magnetic field lines never cross?

Magnetic field lines never cross because they represent the direction of the magnetic force at any point in space.

What happens if magnetic field lines did cross?

the magnetic force would be pointing in two different directions at the same point.

magnetic materials

iron, cobalt, nickel, neodymium

What must me remember when drawing field lines?

Arrows.

Non-magnetic materials

Aluminium, gold, silver, copper

What is a magnet?

A material that exerts a force onto another magnetic material

exerts

puts energy or power into doing something

magnetically hard

Can stay magnetic indefinitely like a bar or horseshoe magnet, producing a permanent magnet

Magnetically soft

Soft materials such as pure iron, can be temporarily magnetised.

What happens if a soft magnetic material is brought in contact with a hard magnetic material?

The magnet field will be induced.

compasses

A compass is a device that tells you which way is north. It has a needle that is magnetized and can move freely.

Where does the needle of a compass point towards

to the Earth's magnetic North Pole

Induction

To create another magnetic field by bringing an opposite pole

permanent magnet

A magnet that will keep its magnetic field indefinitely

temporary magnet

An object that has an induced magnetic field for a short while.

soft magnetic materials

Materials that are easy to magnetize and demagnetize.

hard magnetic materials

A material that is difficult to induce keeping its field indefinitely.

What happens when a current flows through a conductor?

It generates a magnetic field

Unit for current

Amps, A

current

The rate of flow of an electric charge

How could we increase the an electromagnetic force?

Increasing the current ( electricity), increasing the wire length,

What happens when you move a current away from the source of magnetism?

The magnetic strength decreases

What does a loop in flow of current do?

It increases the strength of the field as the fields add together.

Solenoid

a coil of wire with an electric current in it

Why does a solenoid increase the magnetic field strength?

magnetic fields caused by the current in each turn of the coil add together to make a stronger overall magnetic field.

What is the magnetic field of a solenoid similar to?

bar magnet

How could we make the magnetic field of a solenoid stronger ?

By wrapping the solenoid in an iron core making an electromagnet

How is are electromagnets made?

From a solenoid wrapped around iron core.

Advantages of an electromagnet over a permanent magnet

We have more control over electromagnets . You can switch off an electromagnet and vary its current strength.

Uniform field lines

When a magnetic field strength is equal across the whole field.

how to create a uniform magnetic field with two bar magnets?

Placing the opposite poles of two magnets close to each other

Core

soft iron metal which the solenoid is wrapped around

Electromagnet

A non-permanent magnet turned on and off by controlling the current through it.

How can we investigate magnetic fields

Using iron fillings or a plotting compass