Unit 1 - Cost Of Electrical Energy

Question 1

When calculating the amount of energy transferred by a device in kilowatt hours, which units for power and time are used?

Answer 1

Kilowatts and hours.

Question 2

When calculating the energy transferred by a device in Joules, what units are used for power and time?

Answer 2

Watts and seconds.

Question 3

If an electricity meter reads 4579 units, then 2 months later reads 4609 how many kilowatt hours of energy have been used?

Answer 3

Subtract the two numbers to give 30 kilowatt hours or units.

To find the cost in pence multiply this by the cost of one unit (given in a question).

Question 4

Which 3 factors does the cost of running an electrical device depend on?

Answer 4

The power of the device (amount of energy transferred per second).
The amount of time to device is on for.
The cost per unit of electricity set by the electricity company.

Question 5

How much energy in kilowatt hours does a 3000W heater transfer in 3 hours?

Answer 5

3 x 3 = 9kWh