ELECTRICITY AND MAGNETISM

MAGNETISM

Experiment with iron filings to see the magnetic field.

Experiment with iron filings in water and a magnet.

How do we represent magnetic fields? What happens when two magnets attract or repel each other?

The Earth's magnetic field - The magnetosphere

As you can see in the picture, the North Pole (geographical) is actually the South Pole of the Earth's magnetosphere. 

ELECTRICITY

Everything in nature is made of atoms, which contains particles called protons and electrons. Protons have got a positive electric charge, and electrons have got a negative electric charge. When electrons move from the orbit of one atom to the orbit of another atom, electric current is produced.

        We can classify materials by how easily they carry or conduct the electric current

•         Conductors are materials that conduct electric currents quite easily (cooper, aluminium, silver and other metals).
•          Insulators are materials that don’t conduct electric current (plastic, wood and rubber)

              An electric circuit has several parts:

1)      A conductor, such as a metal wire, conducts the electricity along the circuit.

2)      A power source, such as a battery, provides energy in the form of electricity.

3)      A switch is a device that closes and opens a circuit.

4)      The resistor, such as a light bulb, is a device that changes electricity into another form of energy (light or heat).

•                In a closed circuit, electricity can flow and work.
•                 In an open circuit, electricity can´t flow so it can’t work.

ELECTROMAGNETS

Electromagnets produce a magnetic field when they are switched on. But when electromagnets are switched off, the magnetic field disappears.

An electromagnet has got several parts:

1.       An object made of iron, such as a nail, becomes magnetized when the electromagnet is on.
2. 2)      A conductor, such as a metal wire, is wrapped around the iron nail.
3. 3)      A power source, such as a battery, provides electric current.

When the circuit is closed, the electric current passes through the conductor and the iron nail becomes magnetized. When it is open the iron loses its magnetic force.

We can use electromagnets to lift and move heavy metal objects, like old cars.