Chapter 5 Electricity In The Home Flashcards
(18 cards)
What is direct current?
Only flows in one direction
What is alternating current?
Repeatedly reverses it’s direction of flow
What does a mains circuit have?
A live wire which is alternating positive and negative every cycle and a neutral wire at zero volts and is earthed
What is the national grid?
Power station to homes and buildings. Nationwide network of cables and transformers
What is a step up transformer?
Used at power station to transfer electricity from the national grid. They make the size of the alternating potential difference much bigger.
What is a step down transformer?
Used to supply electricity from national grid to consumers. Decreases power supply to 230 volts
How to measure the frequency of an ac supply?
Frequency = 1/ time taken for 1 cycle
What are sockets and plug casings made from?
Stiff plastic, good electrical insulator
What are the different colour wires?
Blue -neutral
Brown-live
Green and yellow-earth
What is the earth wire connected to?
The longest pin and earths the metal case of a mains appliance. Connected to the ground and zero volts. Only carries current if there is a fault
What are the pins made of?
Brass good conductor and doesn’t rust or oxidise
What does a plug contain?
A fuse between live pin and live wire in case too much current passes through and the fuse it melts and breaks the circuit
What is used for the wires?
Copper good conductor and bends easily
Power equation
P=IV
Power equation
Power = current 2 x resistance
Charge flow
Q=It
What happens to charge flow through resistor?
When charge flows through a resistor energy it’s transferred to the resistor and it becomes hotter
E=VxQ
What does an electricity meter do?
Measure how much energy is supplied
