Level: JHS, Basic 7 | Subject: Integrated Science | Strand: Forces and Energy | Topic: Conversion and Conservation of Energy
Read the summary notes first, then try these questions. Go back to the summary notes for this topic.
Part A has 20 tick-box questions. Part B has 5 essay questions with a marking guide at the bottom.
Test Yourself: 20 Objective Questions
Tick one answer for each question, then press Review answer. If your answer is wrong, it will be marked first, then the correct answer will show in green.
1. Changing energy from one form to another is called
2. The law of conservation of energy says that energy
3. An electric fan changes electrical energy mainly into
4. A radio changes electrical energy into
5. A dry cell changes
6. A solar panel changes
7. During photosynthesis, a plant changes
8. When we eat food, our body changes
9. In a falling mango, potential energy changes to
10. A candle changes chemical energy into
11. The energy change in a hydroelectric dam is
12. An electric bulb gives out
13. Energy that is not useful in a machine is called
14. Efficiency is calculated as
15. A machine takes in 200 J and gives out 150 J of useful work. Its efficiency is
16. A machine takes in 400 J and gives out 100 J of useful work. Its efficiency is
17. No machine can be 100% efficient because some energy is always
18. When you rub your hands together, kinetic energy changes into
19. A way to save energy at home is to
20. A petrol engine changes chemical energy into
Essay Questions
- (a) State the law of conservation of energy. (b) Explain what is meant by wasted energy. (4 marks)
- Write the energy change in each: electric iron, loudspeaker, battery torch, solar lantern. (4 marks)
- Describe the energy changes that take place when a ball falls from a height and hits the floor. (4 marks)
- A machine takes in 500 J of energy and gives out 400 J of useful work. Calculate its efficiency. (4 marks)
- Suggest four ways to save energy at home or in school. (4 marks)
Essay Questions: Marking Guide for Teachers and Parents
- (a) Energy cannot be created or destroyed (1), it can only change from one form to another (1). (b) Energy that is not useful, usually heat or sound (1), but it is not destroyed (1).
- Iron: electrical to heat (1). Loudspeaker: electrical to sound (1). Torch: chemical to electrical to light (1). Solar lantern: light to electrical to light (1).
- The ball has potential energy at the top (1). It loses potential energy and gains kinetic energy as it falls (1). On hitting the floor, kinetic energy becomes sound and heat (2).
- Efficiency = useful output ÷ total input × 100% (1) = 400 ÷ 500 × 100 (1) = 80 (1)% (1).
- Any four: switch off lights, use LED bulbs, unplug appliances, close the fridge door, use covered pots, use solar (1 mark each).
Education Always (education.inspiringalways.com). Original practice questions, not official WAEC or BECE questions.