Some domestic devices which produce heat are listed in the following table.

Energy resources

1. The origin of energy resources & forms on Earth is solar energy.

2. Some energy resources are forever (permanent) like the sun, others are renewed like the wind. Fuel is not renewed when used, therefore it’s called non- renewable resource of energy.

I. Choose the correct answer:

1. Mechanical energy is changed into heat energy by means of……………………..

(electric motor – electric heater – friction)

2. When the speed of particles increases, their ……………………..also increases.

(potential – light – thermal)

3. Heat is transferred from cube A to B because the…………….of cube A is bigger .

(size – temperature – density)

4. When ice cubes are added a glass of juice, therefore heat is transferred from……

(ice to juice – juice to ice – ice to the air)

5. Heat is transferred through solids by……………………

(conduction – convection – conduction & convection)

6. Heat is transferred by radiation through………………………..

(solids – liquids – space)

7. The use of ……………………..doesn’t pollute the environment .

(gas heater – solar heater – gas cooker)

8. The gas heater changes …………………..energy into……………………energy.

(chemical into heat – electric into heat – chemical into electric)

9. The Sun is a …………………every resource.

(renewable – permanent – polluting)

10. Solar batteries convert solar energy into …………………..energy.

(chemical – light – electric)

II. Write the scientific term:

III. Give reasons for the following:

1. The heater is placed on the floor.

…………………………………………………………………………………………………………………………………………………………………………………………………………

2. When a cyclist pushes the brakes of his bike to stop it, the tyres of the bikes become heated.

…………………………………………………………………………………………………………………………………………………………………………………………………………

3. People prefer using solar heaters than gas heaters.

………………………………………………………………………………………………………………………………………………………………………………………………………..

Date: 2015-12-24; view: 983