1. Electricity
Current Electricity

2. Current Electricity
In some materials the electrons can wander about between the atoms, these electrons are called FREE ELECTRONS. The more free electrons there are in a solid the better it will conduct electricity.
figure 1(a) - before the wire is connected to a battery
figure 2(a) - the wire is connected to a battery and the electrons move.

3. Conductors and Insulators
Conductors - materials that WILL conduct electricity
All metals
Insulators - materials that WILL NOT conduct electricity
Dry wood, rubber, or plastic

4. Circuits
When one, or more, electrical components are joined together to a cell it is called a circuit. Electricity will not flow if there are any breaks in this circuit.

5. Current An electric current is a flow of charge through a circuit.
An electron is such a tiny amount of charge that we use a bigger unit when studying actual electric currents. The amount of electrical charge is measured in units called amperes.
The electric current in a circuit is measured in Amps using an instrument called an ammeter.

6. Voltage Voltage is the measure of the ENERGY of the electricity.
The potential difference (voltage) is measured between two points on the circuit with a voltmeter. It is really measuring the loss of energy of the electricity between one point and the other.
Measured with a Voltmeter

7. Resistance
The property of a material that resists the flow of electricity through it is called the RESISTANCE of the material.
The more resistance something has the smaller will be the electric current flowing through it for a certain voltage.

8. Total Power
Total Power is the amount of energy the appliance uses. Measured in Watts (W).
Electrical Power = Voltage x Current
P = V x I
Example: What is the total power of a 20V toaster taking 10A?
Formula: P = V x I Unknown: P = ? Known:V = 20V, I = 10A
P = (20V) x (10A)
P = 200W
Known:V = 20V, I = 10A
Formula: P = V x I
Unknown: P = ?
P = (20V) x (10A)
P = 200W