Revision Questions

1. Give 3 reasons why electrical energy is so useful to us.

2. Name a device which converts electrical energy into a) kinetic energy, b) sound energy, c) heat energy

3. What is power measured in?

4. A kettle has a power of 2.5kW. How many joules of energy does it transfer every second?

5. Kettle A has a power or 2.5kW, kettle B has a power of 3.5kW. Which will take less time to boil a litre of water?

6. Complete this table

7. How does the electricity company know how how many units of electricity you have used?

8. If one unit costs 9p how much does it cost to use each of the devices in the table above for 24 hours non-stop?

9. What is the biggest problem with transmitting electricity long distances?

10. What is the national grid?

11. What does a step up transformer do to a) the voltage from a supply?, b) the current from a supply?

12. Why is electricity transmitted at high voltages?

13. Why is the voltage stepped down to 240V before it comes to our homes?