Transformation of Energy

25 Grade 8 Integrated Science questions on Transformation of Energy, with worked marking schemes. 25 questions are available on this topic in full.

1. Question 1

   1 mark

   Which energy transformation takes place in a battery-operated torch?

   A. Light → electrical → chemical

   B. Chemical → electrical → light

   C. Nuclear → heat → light

   D. Sound → kinetic → light

   (1 mark)

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2. Question 2

   1 mark

   A charcoal jiko is used to heat water for cooking. The energy transformation involved is:

   A. Light energy to heat energy

   B. Electrical energy to heat energy

   C. Chemical energy to heat energy

   D. Heat energy to chemical energy

   (1 mark)

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3. Question 3

   1 mark

   Which energy transformation takes place when a dry cell is used to run a small electric motor?

   A. Chemical energy to electrical energy to kinetic energy

   B. Kinetic energy to electrical energy to chemical energy

   C. Light energy to electrical energy to kinetic energy

   D. Electrical energy to chemical energy to kinetic energy

   (1 mark)

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4. Question 4

   4 marks

   A student claimed that a machine can produce more energy than it is supplied with.

   (a) Using the law of conservation of energy, explain why this claim is not correct. (2 marks)

   (b) Explain why some of the energy supplied to a machine appears to be 'lost'. (2 marks)

   (4 marks)

   Marking scheme

   (a) Energy can neither be created nor destroyed, only transformed (1 mark); therefore a machine cannot give out more energy than it receives (1 mark). (b) The energy is not truly lost but is transformed into other forms such as heat and sound due to friction (1 mark); these forms are not useful/wanted so they appear as 'losses' (1 mark).

5. Question 5

   4 marks

   Kenya generates electricity from several sources.

   (a) State the energy transformation that occurs in a hydroelectric power station such as Seven Forks. (3 marks)

   (b) State one advantage of using hydroelectric power over a diesel generator. (1 mark)

   (4 marks)

   Marking scheme

   (a) Potential energy of stored water is converted to kinetic energy as it falls (1 mark); kinetic energy turns the turbines (1 mark); the turbines drive generators that convert it to electrical energy (1 mark). (b) Any one: it is renewable / cleaner (no harmful gases/pollution) / cheaper to run in the long term (1 mark).

6. Question 6

   5 marks

   Energy can be transformed from one form to another in various devices.

   (a) State the main energy transformation that takes place in each of the following:

   (i) An electric bulb that is switched on

   (ii) A solar panel

   (iii) A car battery being charged (3 marks)

   (b) State the law of conservation of energy. (2 marks)

   (5 marks)

   Marking scheme

   (a) (i) Electric bulb: electrical energy is transformed into light energy (and heat energy). (ii) Solar panel: light (solar) energy is transformed into electrical energy. (iii) Car battery being charged: electrical energy is transformed into chemical energy. (b) The law of conservation of energy states that energy can neither be created nor destroyed but can only be transformed (changed) from one form to another.

7. Question 7

   1 mark

   When a torch is switched on, the energy transformation that occurs in the bulb is:

   A. Electrical energy to light and heat energy

   B. Chemical energy to electrical energy

   C. Light energy to electrical energy

   D. Heat energy to chemical energy

   (1 mark)

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8. Question 8

   1 mark

   Which of the following is a form of energy?

   A. Heat energy

   B. Volume

   C. Mass

   D. Density

   (1 mark)

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9. Question 9

   4 marks

   State the law of conservation of energy and explain it using an example.

   (4 marks)

   Marking scheme

   The law of conservation of energy states that energy cannot be created or destroyed, but can only be transformed from one form to another.

   Example: When a ball is thrown upwards, kinetic energy is converted to potential energy. At the highest point, all kinetic energy becomes potential energy. As it falls, potential energy converts back to kinetic energy.

10. Question 10

    5 marks

    Energy can be transformed from one form to another in different devices.

    (a) State the energy transformation that takes place in each of the following:

    (i) An electric bulb (1 mark)

    (ii) A solar panel (solar cell) (1 mark)

    (iii) A loudspeaker (1 mark)

    (b) State the law of conservation of energy. (2 marks)

    (5 marks)

    Marking scheme

    (a) (i) Electric bulb: electrical energy to light energy (and heat energy). (ii) Solar panel: light (solar) energy to electrical energy. (iii) Loudspeaker: electrical energy to sound energy. (b) The law of conservation of energy states that energy can neither be created nor destroyed but can only be transformed (changed) from one form to another; the total amount of energy in the universe remains constant.

11. Question 11

    1 mark

    A solar panel converts

    A. light energy to electrical energy

    B. electrical energy to light energy

    C. chemical energy to heat energy

    D. sound energy to electrical energy

    (1 mark)

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12. Question 12

    1 mark

    During photosynthesis in a maize plant, the energy transformation that takes place is:

    A. Heat energy to chemical energy

    B. Chemical energy to light energy

    C. Light energy to heat energy

    D. Light energy to chemical energy

    (1 mark)

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13. Question 13

    1 mark

    The law of conservation of energy states that energy

    A. always decreases over time

    B. cannot be created or destroyed, only transformed

    C. can be created from nothing

    D. can only exist in one form

    (1 mark)

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14. Question 14

    4 marks

    (a) State the energy transformation that takes place in each of the following devices:

    (i) electric bulb; (ii) battery (dry cell) in use. (2 marks)

    (b) State the law of conservation of energy. (2 marks)

    (4 marks)

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15. Question 15

    5 marks

    Energy can be transformed from one form to another in various devices.

    (a) State the main energy transformation that takes place in each of the following:

    (i) an electric bulb (ii) a solar panel (iii) a battery in a torch. (3 marks)

    (b) State the law of conservation of energy. (2 marks)

    (5 marks)

    Marking scheme

    (a) (i) Electric bulb: electrical energy to light energy (and heat energy). (ii) Solar panel: light/solar energy to electrical energy. (iii) Battery in a torch: chemical energy to electrical energy. (1 mark each) (b) The law of conservation of energy states that energy can neither be created nor destroyed but can only be transformed/changed from one form to another. (2 marks)

16. Question 16

    1 mark

    In an electric bulb, electrical energy is transformed into

    A. nuclear energy and magnetic energy

    B. kinetic energy and potential energy

    C. sound energy and chemical energy

    D. light energy and heat energy

    (1 mark)

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17. Question 17

    1 mark

    In a car engine, chemical energy from fuel is mainly converted to

    A. kinetic energy and heat energy

    B. light energy and sound energy

    C. nuclear energy

    D. potential energy only

    (1 mark)

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18. Question 18

    4 marks

    Describe the energy transformations that take place in the following:

    (a) A hydroelectric power station

    (b) A wood fire

    (4 marks)

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19. Question 19

    3 marks

    A learner switched on an electric iron box to press school uniforms.

    (a) State the energy transformation that takes place in the iron box. (2 marks)

    (b) Name the law that governs energy transformations. (1 mark)

    (3 marks)

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20. Question 20

    1 mark

    The law of conservation of energy states that energy:

    A. Is destroyed each time it is used

    B. Is created whenever a machine is switched on

    C. Can be created but not destroyed

    D. Can neither be created nor destroyed but only transformed from one form to another

    (1 mark)

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21. Question 21

    1 mark

    A solar panel on the roof of a house in Garissa is used to charge a phone. The main energy transformation taking place in the solar panel is:

    A. Chemical energy to light energy

    B. Electrical energy to light energy

    C. Light energy to electrical energy

    D. Heat energy to electrical energy

    (1 mark)

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22. Question 22

    1 mark

    At the Seven Forks hydroelectric power station, the energy of falling water is used to generate electricity. The correct sequence of energy transformation is:

    A. Chemical energy to kinetic energy to electrical energy

    B. Potential energy to kinetic energy to electrical energy

    C. Electrical energy to kinetic energy to potential energy

    D. Kinetic energy to chemical energy to electrical energy

    (1 mark)

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23. Question 23

    1 mark

    A drum being beaten converts kinetic energy to

    A. sound energy

    B. chemical energy

    C. nuclear energy

    D. light energy

    (1 mark)

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24. Question 24

    4 marks

    For each of the following devices, state the main energy transformation that takes place:

    (a) A car battery-powered radio (2 marks)

    (b) An electric bulb (2 marks)

    (4 marks)

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25. Question 25

    1 mark

    Energy can be defined as the ability to

    A. create matter

    B. produce sound only

    C. do work

    D. destroy matter

    (1 mark)

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