GCSE Physics: Cost of Electricity
The amountof electricical energy used by an appliance is given by:Energy (J) = Power (W) * time (s)
The higher the power, the quicker the appliance uses electrical energy. When you are charged, you are charged for the number of KW hours of energy rather the number of Joules.
1KWh=1000 * 60 * 60
= 36000000J
= 8-10 pence
| Appliance | Power (W) | Power (kW) | Time (s) | Cost |
| Heater | 2000 | 2 | 2 | 32p |
| Kettle | 2500 | 2.5 | 2.5 | 30p |
| Lamp | 100 | 0.1 | 8 | 6.4p |
| TV | 50 | 0.05 | 5 | 2p |
| Hi-Fi | 30 | 0.03 | 0.5 | 0.12p |