changes direction 50 times per seconds
mains plug socket
more dangerous for electric shocks
flows in one direction around the circuit
-rectrfied mains supply
Dangers of Electricity
When there is too much current in the wire this causes over heating and then a fire.
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.
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.
This is a resettable fuse. It is more convinient yet more expensive.
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.
Working out power, current and Energy
power(W)= volts(v) x amps(A)
e.g 12v x 5A = 60W
Energy (E)= voltage(V) x current(I) x time (minutes)
Power (W)= energy(E) / time (minutes)
current (I)= power (W)/ voltage (V)
Current = power(W)/ voltage(V)