Electricity - Domestic Electricity Flashcards
what is the voltage of the uk domestic mains supply
230
what uses direct current
cells and batteries
what is the colour and role of the live wire
brown
provides alrwernating pd
what is the colour and role of the neural wire
blue
completes circuit and carries away current
what is the colour and role of the earth wire
yellow and green
stops appliance becoming live
what happens when you touch the live wire
large pd across body and current flows through you which causes an electric shock. you create a connection between the live wire and the earth
why is it dangerous to touch a live wire if the plug is turned off
still pd across wire
why is energy transferred when a charge flows
because charge does work against the resistance of the circuit
what is the equation for energy transferred using power
= power x time
what does a power rating tell you
maximum amount of energy transferred between stores per second
why may an appliance with more power not transfer energy usefully
bad efficiency
describe the rise and fall in pd of of charge as it moves around a circuit
charge gains energy at battery , increasing pd.
charge releases energy at resistors, dropping the voltage
these are rises and falls
energy transferred = charge x potential difference
a bigger change in pd means more energy is transferred
what is the national grid
network of cables and transformers that connect power stations to consumers
why is a low current used in the national grid
wires heat up and energy is lost when current is high
