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

Important points on Unit (3) Concept 3.3

Renewable energy resources

Windmills Watermills

Energy used • Kinetic energy of wind. • Kinetic energy of water.
Advantages
• Low cost. • Low cost.
• Renewable energy • Renewable energy

resource. resource.
• The water supply may
• Sometimes the wind
doesn’t blow so they dry up and it doesn’t
don’t move, so they are move so they are unable
unable to do their job. to do their job.

Disadvantages

• The sun is a star which is made up of hydrogen and helium gases.
• The sun has a photosphere which is the gas layer at the surface of the

sun where the light we see is emitted.
• The solar energy that is produced by the sun contains a type of energy

called (radiant energy) radiation which is found in the sunrays.

Uses of solar energy:

1. It is a direct source of thermal energy.
2. In green house radiant energy converted into thermal energy.
3. In warming houses.
4. In cooking food.
5. In heating water.

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