Magnetism

1) What is a Magnet ?
Some elements have an atomic structure that creates a magnetic field.
They are objects that produce magnetic fields (metals - iron, nickel, cobalt)
They can be made permanently magnetic by exposing them to a magnetic field using eletric current.

2) How do you make a permanent magnet ?
A magnetic field is created when electrons move around the neucleus.
Some elements have an atomic structure that allow the negatively charged particles (electrons) to move around the nucleus (that contains the proton and neutron)
When the electrons are in motion, they create a magnetic field.
Elements that have strong magnetic behaviour are called ferromagnetic elements.

3) What is Steel made up of ?
Steel is an alloy that is a substance formed by combining two or more metals.
Steel is a combination of Iron, Carbon (<2%) and other elements.
Steel is mostly iron, so is magnetic.

4) What is a Solenoid ?
This is a long coil of wire.

5) What is a Magnetic Field ?
This refers to the area around an object that is affected by a magnetic force (non contact)

6) Can magnetic forces affect the air around them ?
Yes. An object that has a magnetic force can affect another object without the objects touching.

7) Can you give the names of some metals that have a very low magnetic field ?
Most metals have a very low magnetic field, gold, silver, aluminium.

8) What is Brass mad up of ?
Brass is a combination of Copper and Zinc.

9) Can you draw the magnetic field lines for a bar magnet ?
North pole and South pole

10) What happens when these two poles get closer together ?
North + North - They Repel each other.
North + South - They Attract each other.

11) What is an Electromagnet ?
This is a magnet that can be switched on and off.
An electric current flowing through a coil of wire, will create a magnetic field.
Because you can turn the current on and off, you can therefore turn the magnetic field on and off.
Iron is used to create electromagnets.

12) What is an Electromagnetic Field ?
When an electric field and a magnetic field join together this combined field is called an electromagnetic field (EMF).
This invisible field is often called radiation.

13) Can you describe the magnetic field produced when current flows through a wire ?
When a current flows in a wire, it creates a circular magnetic field around the wire.
The direction of the current and magnetic field can be found using the right hand grip rule.

14) How could you increase the magnetic strength of an electromagnet ?
There are two ways:
Increase the current
Increase the number of turns in the coil

15) Can you describe how you build an electric motor ?
It is made from a loop of wire between two magnets
When current flows through the wire, a magnetic field is created around the wire
The magnetic field from the wire is attracted and repelled from the magnets that are stationary.
This force causes the top of wire to turn.