P5 Flashcards
what is direct current?
-charge flows in One Direction only
what is alternating current?
-it can reverse direction
-mains electricity
-UK mains pd supply is 230V
-frequency of 50Hz =changes direction back again 50 times a seconed
how do you draw alternating current
-a line with hill looking things
how do you draw direct current
- a straught line
what is mains circuits
-has a live and neutral wire
-live =alterbsting
-neutral= completes circuit
why is the neutral wire safe and the live wire are dangerous?
neutral wire is connected to earth so PD between them is 0
-the live wire is dangerous because the PD between the earth and the wire is 230V
what is a step up transformer
-used to transfer energy to national grid
-used to increase PD
what is a step down transformer
-used to supply the electricity from national grid to consumers
-decrease PD to 230 for homes and offices
why do you increase PD in the national grid
-current in the cables is decreased
- so energy loss to resistance heating in the cables is less
why is plastic used in plug
-because it’s a good electrical insulator
why are the plug pins made of brass
-more dense so more durable
why do the wires have plastic around them
to further prevent an electric shock
3 saftey procautions of plugs
-plastic - keeps from chocks
-earth wire -gets current to ground
-funny shape -maks sure wires aren’t touching
what is an electrical insulator
-does not allow electricity to flow
why are the wires in a plug made from copper
-good electrical conductor
how does a fuse work
-connected to live wire and melts when too much current flows through
what is a short circuit
-love wore touches a neural wire and causes fire
what side and colour is the live wire
-side= right
-colour =brown
what side and colour is the earth wire
side =middle
colour=geeen and yellow
what side and colour is the neautal wire
side=left
colour=blue
what is the equation linking power and time
every = power x time
what is the equation linking current and PD
-power =cirrent x PD
