PHYSICS- Electricity in the home

What is potential difference?

a measure of energy , per unit of charge, transferred between 2 points in a circuit.

why is energy transferred when a charge moves?

because the charge does work against the resistance of the circuit and work done is the same as energy transferred.

what is the power of an appliance?

the power of an appliance is the energy that it transfers per second, so more energy that is transferred, the higher the power.

what happens whenever energy flows?

it has to overcome resistance of a circuit and therefore work is done when charges flow, the amount of work done depends on the amount of charge that flows and potential difference

what is the function of the power station?

transfers the energy supply into electrical energy and they use smaller numbers of large power stations

what is the function of step-up transformers?

Step-up transformers increase the voltage (and reduces the current) through the wires

Why is the national grid efficient?

A low resistance and a low current mean that the transmission wires will not heat up as much. As a result, most of the power is delivered to the consumer, and not lost through the wires.

what is DC current ?

Direct current, the current only flows in one direction

How are alternating currents produced?

by alternating potential difference in which the positive and negative ends keep alternating

how are direct currents produced?

positive and negative ends of the source are fixed.

what is the live wire?

brown wire which carries alternating pd from the supply, 230v

what is the neutral wire?

blue wire which completes the circuit, 0v

what is the Earth wire?

yellow and green wire, a safety device which stops appliance becoming live. 0v

what happens if you touch the live wire?

A large potential difference is produced across your body and a current will flow through you

what are the dangers of live and Earth wire touching?

if the two wires were to touch then the circuit will be complete and the dangers of electric shock and a fire will be very likely

What does the amount of energy an appliance transfers depend on?

how long the appliance has been turned on for and the power of the appliance

how is work done in a circuit

work is done when a charges flows though a circuit

What is the national grid?

the network of cables and transformers that covers the UK and connects power stations to consumers

what does the national grid do?

Transfers electrical power from power stations to homes, industry etc

what is the function of step down transformers?

Step-down transformers decrease the voltage (and increases the current) through the wires for domestic use

what is AC current?

alternating current, it often changes direction

what are the three core cables?

live, earth and neutral

give two examples of electrical appliance which transfer energy electrically

motor, kettle, speaker

what are power ratings?

maximum safe power that they can operate at

what is the function of transmission cables?

transfer electricity