Electricity

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  • Created by: BellaS
  • Created on: 30-03-15 14:04

AC/DC

Alternating current 

changes direction 50 times per seconds

mains plug socket

more dangerous for electric shocks

Direct current

flows in one direction around the circuit

-batteries

-solar cells

-rectrfied mains supply

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Dangers of Electricity

Electrical heating-

When there is too much current in the wire this causes over heating and then a fire.

Electric shock-

When something touches a live wire, they will experiance a electric current passing through their body.

Direct current- It hurts but nothing serious

Alternating current- this can kill you

Electricity + water-

When a live wire touches the water, it too then becomes live. When this live water is touched the object touching it will receive an electric shock.

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Saftey devices

Fuse-

The fuse is a weak point that will melt when a current is too high and unsafe for the wire (which could cause electric fires). When the fuse melts the circuit breaks.

Circuit breaker-

This is a resettable fuse. It is more convinient yet more expensive. 

Earth wire- 

The earth wire connects the metal case of an object, E.g a laptop, to the earth.

If a fault develps the case becomes live, the large current flows through the case, down the earth wire to the eath. it is a safer way to get the current to the earth.

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Working out power, current and Energy

Power

power(W)= volts(v) x amps(A)

e.g 12v x 5A = 60W

Energy

Energy (E)= voltage(V) x current(I) x time (minutes)

Power (W)= energy(E) / time (minutes)

current (I)= power (W)/ voltage (V)

Current

Current = power(W)/ voltage(V)

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