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Delta Modern Language School
Grade 4
Date ......./......./………

Exercises on Unit (3) concept (3)

Q. (1) – Complete the following sentences: -

1-…………………... use solar energy to generate electricity.
2-The device that uses electric energy to produce kinetic energy is …………………
3-Using watermills has some advantages such as ………….……and……….………….
4-By increasing number of blades, windmills generate ………………energy
5-All mills depend on ………………. energy to be operated
6-The primary source of energy on Earth is …………………….
7-The Sun provides us with …………………and………………….
8-The Sun is made up of ……………. and ………………… gases
9-We use solar energy in….....................and………………
10-The turbines generate electricity by using kinetic energy of wind are……………
11-Water flows through …………….in dams to generate electricity.

Q. (2) – Put (√) in the front of the right statement and (×) in the front of

the wrong one: -

1-Windmills use solar energy to generate electricity. (…….)
2-The photosphere is a gas layer at the surface of the moon. (…….)

3-The reactions on The Sun surface produce huge amount of light and heat. (…….)
4-Modern windmills have a smaller number of blades than old mills. (…….)
(…….)
6-All mills depend on thermal energy to produce electricity.

7-Without the Sun life on Earth will disappear. (…….)

Q. (3) – Choose the correct answer: -

1-Places can help farmers to grow tropical crops is winter is ……………….

a) hydroponic system. b) garden. c) greenhouses. d) lakes.

2-When the wind blows from the side of wind turbines the blades rotate…………….

a) slower. b) faster. c) a & b. d) no correct answer.

3-When the number of blades of windmill increases it moves ……………….

a) slower. b) faster. c) a & b. d) no correct answer.

4-…………. are built on rivers to control the water flow.

a) Towers. b) Houses. c) Dams. d) Mills.

5-The type of electricity which is produced from dams is called……………………

a) hydroelectricity. b) solar energy. c) electromagnetic. d) light energy.

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