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## TRANSFER OF HEAT

Encircle the correct answer from the given choices.

1. In solids, heat is transferred by:

(b) conduction.

(c) convection

(d) absorption

2 What happens to the thermal conductivity of a wall if its thickness is doubled?

(a) Becomes double

(b) remains the same

(c) Becomes half.

(d) becomes one fourth

3 Metals are good conductor of heat due to the:

(a) Free electrons .

(b) big size of their molecules

(c) small size of their molecules

(d) rapid vibration of their atoms

4 In gases, heat is mainly transferred by:

(a) Molecular collision

(b) conduction

(c) convection.

5 Convection of heat is the process of heat transfer due to the molecules

(a) Random motion

(b) downward movement

(c) upward movement

(d) free movement.

6 False ceiling is done to:

(a) Lower the height of ceiling

(b) keep the roof clean

(c) cool the room

(d) insulate the ceiling.

7 Rooms are heated using gas heaters by:

(a) Conduction only

(d) convection only

8 Land breeze blows from:

(a) See to land during night

(b) sea to land during the day

(c) Land to sea during night.

(d) land to sea during the day

9 Which of the following is a good radiator of heat?

(a) A shining silvered surface

(b) A dull black surface.

(c) A white surface

(d) A green colored surface

10 Styrofoam is a:

(a) Conductor

(b) Semiconductor

(d) None of them

11 Unit of thermal conductivity is:

(a) Wm-1 K-1

(b) Wm-2K-1

(c) Wm-1 K-1

(d) Wm2K-1

12.       Ice is an:

(a) Good conductor

(c) Perfect Conductor

(d) None

13.       How many methods of transmission of heat there are :

(a) 1

(b) 2

(c) 3

(d) 4

14.       Which of the following is best for insulation?

(a) Glass

(b) Air

(c) Brass

(d) Fiber glass

15.       Transmission of heat from one body to another body by the interaction of atoms and electrons:

(a) Conduction

(b) Convection

(d) All of above

16.       Transfer of heat by the actual movement of molecules:

(a) Conduction

(b) Convection

(d) All of above

17.       Geysers work on the principle of:

(a) Conduction

(b) Convection

(d) All of above

18.       Transmission of heat by waves without affecting medium on its way:

(a) Conduction

(b) Convection

(d) All of above

19.       Ventilation in our houses is only possible due to:

(a) Conduction

(b) Convection

(d) All of above

20.       Heat from sun reaches on earth by:

(a) Conduction

(b) Convection

(d) All of above

21.       Water is a:

(a) Good conductor

(b) Poor conductor

(c) Super conductor

(d) Insulator

22.       Feathers of the birds are:

(a) Conductor

(b) Semiconductor

(c) Insulators

(d) None of them

23.       Land and sea breezes are due to:

(a) Conduction

(b) Convection

(d) All of them

24.       Global warming in the world is due to:

(a) Greenhouse effect

(b) Land and sea breezes

(d) None of them

25.       Black surfaces are   emitter:

(a) Best

(b) Good

(c) Worst

(d) Poor

26.       Shining silvered surfaces are ———– reflector:

(a) Best

(b) Good

(c) Worst

(d) Poor

27.       Coloured surfaces are   absorber

(a) Best

(b) Good

(c) Worst

(d) Poor\

28.       The gases in the Earth’s atmosphere, which causes the greenhouse effect:

(a) Carbon dioxide

(b) Water vapors

(c) Both a & b

(d) None of them

29.       Which one is (are) the insulator (s)?

(a) Cork

(b) Cotton

(c) Rubber

(d) All of them

30.       Movement of water on heating is shown by the crystal of:

(a) Sodium chloride

(b) Potassium permanganate

(c) Calcium carbonate

(d) None of them