Electricity

ACDC

- Alternating Current is when the current is constantly changing direction. The circuits electrons are coming from a power supply not battery and it is easy to use a transformer to increase/decrease the potential difference supplied. We use transforemers alot when electricity is transfered from powerstations to our homes. In the UK alternating current has a frequency of 50 Hz (switches direction 50 times a second). It also has a potential difference of 230v.

- Direct Current is from a battery (cell) it is when the electrons in the current can only travel in one direction.

- We can use an oscilloscope to see the pattern of a current. AC looks wavy as the current is always moving up/down. DC looks like a straight line as the potential difference isn't changing. Maximum potential differnce is how large the potential differnce is at the peak of the wave. Frequency = 1/time between peaks.

Plugs

- Live wire is brown and is connected on the right side and the fuse, it always carries a current as long as appliance is plugged in (not neccesserilly on).

- Neutral wire is blue and is connected to the left side. It only carries a current if appliance is switched on.

- Earth wire is green and yellow striped and is connected to the centre. The earth works with the fuse to protect us from shocks. Current shouldnt get to high because of this and therefore the wire in the fuse shouldn't melt.

Fuses

- Contains a thin piece of wire that conducts electricity. If the current in a circuit becomes dangerously high the wire in the fuse melts and the current is cut - preventing electricution and circuit breaking.

- Appliances with metals cases can be very dangerous as if a wire comes loose and touches the metal case, it can become live. (current running through it) To prevent this the metal case is attached to the earth cable, which…