Electricity notes

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Circuit symbols:

Batteries and cells:

A battery is made up from joining multiple cells together.

Static Electricity:

Electrons don't move through the material.

if you rub the material the electrons fall off

the material has a positive charge

It is attracted to the electrons on the outside on any other material

Current electricity:

Caused by the movement of electrons through a material

Electrical current is measured using an ammeter

Current:

Current is measured of how much electric charge flows through a circuit

the more charge that flows, the bigger the current

current is measured in units called amps

Energy Transfer:

Voltage:

Voltage is a measure of the difference in electrical energy between two parts of a circuit. The greater the difference, the greater the voltage. It is measured in volts. Symbol = V. 230V is bigger than 12V

The more cells the bigger the voltage

Electrical resistance:

How difficult it is for electrons to move through an objrct

measured in Ohm's

Conductors have a low resistance

Insulators have a high resistance.

Ohm's Law:

R=V/I

If graphed, it gives a linear rule'

The electric

Series an Parallel circuits:

If there are no branches it is a series circuit

if there are branches, it is a parallel circuit

Series Circuit:

If you put more lamps, the dimmer it will be

If a lamp breaks, the circuit is broken, and all components stop working

It's useful as a warning if one component in the circuit has failed.

It uses less wiring

Parallel circuit:

If a lamp breaks, the components on the other branches keep working.

The lamps stay bright if you add more lamps

They are useful if you want everything to work, even if one component fails

are homes are wired up with parallel circuits.

Direct and Alternating Currents:

Direct Current (DC):

The electric current supplied by a cell or a battery

It flows in one direction only

Alternating Current (AC):

The electric current provided by your home by power stations

It changes direction about 100 times every second

Electricity in the home:

Houses use AC because it is easier and cheaper to generate.

It is also cheaper and easier to distribute widely over large distances in Australia

In Australia, electricity, is generally supplied to homes in 240 V

Most electrical devices, aren't designed to use 240 V (computer printers, requires 9-12 V)

A transformer, usually attached to the lead, is plugged into the power point

The transformer reduces the voltage from 240 V to the 9 or 12 V required

Electrical safety:

A 240 V AC house hold power supply can kill

power points have 3 sockets, AC flows between the two top sockets through the appliance

The third socket, is called the earth socket, it is connected to the ground

Fuses and safety switches

Fuse: a thin wire that melts of the current becomes too strong

The fuse disappears, and the current is broken

they work to slowly to stop people from getting an electric shock