P1.3

Question 1

What energy is wasted in the process of energy transfers with a microwave?

Answer 1

Sound energy

Question 2

Explain how the amount of time an appliance is switched on effects the amount of energy it transfers

Answer 2

The longer an appliance is switched on, the more energy is transferred

Question 3

Give the formula to find energy

Answer 3

Energy = power x time
or
E = P x T

Question 4

If an appliance is switched on for 5hours, and it uses 200 kilowatts of power, how much energy is used?

Answer 4

5 x 200 = 1,000

answer = 1,000

Question 5

Explain what is meant by the term ‘payback time’

Answer 5

The time it takes to make up for the initial cost

Question 6

A new gas boiler for a house costs £3,000 but saves £250 per year. What is its payback time?

Answer 6

12 years
(3000 divided by 250 = 12 years)

Question 7

What is the formula for payback time

Answer 7

Total cost divided by

Question 8

Give ONE example of an energy transfer used in every day life

Answer 8

Any one from -

• microwave (electrical energy - thermal & kinetic energy)
• mobile phone (electrical energy - light & thermal & sound energy)