Electricity In The Home Flashcards
What does the number of Hertz represent?
The amount of times current changes direction in a second.
E.g. 50 Hertz = 50 times per second.
What would direct current look like in a current - time graph?
Straight line
What would alternating current look like in a current - time graph?
Wavy line going above and below the time line
Describe what a two way switch looks like.
Check notes.
Label the parts of a plug.
Check notes.
What is a fuse?
A protection device.
They have a wire inside them that melts and breaks the circuit if the current becomes too strong. They are rated according to the current they carry.
How do you calculate fuse rating?
P = I x V
Power = current x voltage
(Mains Potential difference (voltage) always 240V)
What is the function of the live and neutral wires?
Carries current to and from the appliance respectively. There are equal but opposite currents in these wires.
What is the function of the earth wire?
Does not normally carry a current unless there is a fault such as a short circuit. When this happens, the current flowing in the metal body of the appliance is conducted to earth, avoiding an electric shock.
By law, all metal bodied appliances must be earthed.
What is double insulation?
The body of an appliance is covered in a non conducive material which makes electric shocks impossible.
The symbol for this is a square inside a larger square.
What is a kWh?
Kilowatt-hour, the unit of electricity billing companies use to calculate how much electricity someone uses.
How do you calculate the cost of electricity?
Cost = Cost per unit x number of units
How do you calculate the cost of electricity if the number of units is not known?
Cost = (power in KW) x (time in hours) x (unit cost)
