GCSE Standard Questions: Electricity in the Home
Q18. The electricity supply to a house has a potential difference of 230 V.
The table below shows the current in some appliances in the house.
Appliance |
Current/A |
Dishwasher |
6.50 |
DVD player |
0.10 |
Lamp |
0.40 |
TV |
0.20 |
(a) Calculate the total power of all the appliances in the table
Total current = 6.50 + 0.10 + 0.40 + 0.20 = 7.20 A
P = IV
P = 7.20 x 230 = 1656 W
[3 marks]
(b) Each appliance in the table is switched on for 2 hours.
Which appliance will transfer the most energy?
Give a reason for your answer.
The dishwasher because it draws the largest current and therefore transfers the most energy per second or power (as energy transferred each second is the product of potential difference and current drawn).
[2 marks]
(c) The average energy transferred from the National Grid every second for each person in the UK is 600 J.
Calculate the average energy transferred each year from the National Grid for each person in the UK.
Number of seconds in a year = 365.25 (average number of days) x 24 (hours) x 602 (minutes and seconds)
= 31557600
Energy transferred in a year = 32,000,000 x 600
= 1.9 x 1010J
[3 marks]
(Total 8 marks)
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