How much energy do we use? - OCR 21C

1

What are the correct units for energy transferred (work done)?

2

What is the correct unit for power?

3

Which of the following is a definition of power?

4

A hairdryer transfers 10,000 J of energy in 4 s. What is its power?

5

Which of these cannot happen to energy?

6

A 60 W lamp is left on for 20 s. How much energy is transferred in this time?

7

In an electric kettle, what energy is not wasted?

8

How can the thermal store of a house be prevented from dissipating for as long as possible?

9

What is the efficiency of Christmas lights that give out 10 J of light radiation for an electrical input of 200 J?

10

How might a toy car be made more efficient?