1. A hairdryer with a power
rating of 1.5 kW means that it transforms 1500 joules of electrical
energy each second.
2. A television with
a power rating of 60 W that transformed 600 J of energy was switched on
for 10 seconds
3. Total units used
= 03102 - 02586
Total
units used = 516 kWh
Cost
of electrical energy used = 516 x 9 pence
Cost
of electrical energy used = £46.44
4. Table to find the cost
of using the electrical appliances. The cost is 9 pence per kilowatt hour.
| Devices |
Power
rating |
Time |
Cost |
| Electric
cooker |
5 kW |
2
hours |
5 x 2 x 9 = 90 pence |
| Light
bulb |
100 W |
2 hours |
0.1 x 2 x 9 = 1.8 pence |
| Computer |
110 W |
30
minutes |
0.11 x 0.5 x 9 = 0.495 pence |
| Kettle |
2 kW |
15 minutes |
2 x 0.25 x 9 = 4.5 pence |
