P1.3

Question 1

How can the cost of using electrical appliances be worked out?

Answer 1

Only if we know the amount of energy transferred in a given time.

Question 2

What is the equation used to find the energy transferred from an appliance?

Answer 2

Energy transferred in joules (E) =power in watts (P) x time in seconds (t)

Question 3

What is the cost of electricity supplied by the mains measured in?

Answer 3

pence per kilowatt-hours

Question 4

What is the difference between watts and kilowatt-hours?

Answer 4

Watts are a unit of power, but kilowatt-hours are a unit of energy

Question 5

How can kilowatt-hours be calculated?

Answer 5

energy transferred in kilowatt-hours = power in kilowatts x time in hours

Question 6

Name some different examples of energy transfers.

Answer 6

Light bulbs, display screens: electricity-light
kettles, heaters:electricity-energy transfer by heating
motors:electricity-kinetic energy
radios:electricity-sound energy

Question 7

how can kettles be used more efficiently?

Answer 7

by only heating the amount of water needed