Electricity In The Home Flashcards
What’s the difference between A.C and D.C
A.C supply is one in which current is continually changing direction in the live and neutral wires
D.C is one in which the conventional current always flows in one direction from positive to negative
What is a one way switch
A switch acts as a make-or-break device to switch a current on or off. When the switch is open there is air between the conducting contacts. Since air is an insulator the circuit is broken. The rocker can then be pushed to press the conducting contacts together thus creating a complete circuit
What is a two way switch
Two switches can make or break the circuit. E.g landing lights in houses. Both switches must be in the same position for a current to flow.
How is a 13A plug wired
Neutral wire (blue) left
Earth wire (green and yellow striped) middle
Live wire (brown) right
What is the function of the live wire
The live wire is the dangerous wire in a mains voltage system in which the voltage is changing.
What is the function of the neutral wire
Carries current out of the appliance, is permanently at 0V
What does a fuse do
A fuse prevents damage to an appliance. Protects the appliance from internal damage and any fire risk. They do this by the fuse wire melting and breaking if a current is too large flowing. They are always connected into the live wire so that they should melt and blow so the appliance does not remain live.
Equation for finding fuse rating for an appliance
P=IV
What is the function of the Earth wire?
The Earth wire provides a very low resistance path for current down to Earth to prevent a fatal electric shock in a human.
Define doubly-insulated
Some electrical appliances have an outer casing made from insulating material such as plastic. The user could never get an electric shock therefore pointless for these appliances to include an Earth wire
Why is the positioning of the switch to be placed on the live wire side of the circuit important?
If the switch was on the neutral side the appliance would be off but it would still be live as it would disconnect the neutral wire but not break the live wire.
How to calculate cost from meter readings?
Cost = number of units x cost per unit
What is a kilowatt-hour?
The energy used when a 1kW appliance is used for 1 hour
How to calculate the cost of an electrical appliance using power rating
Cost = (power in kW) x (time in hours) x (unit cost)
