Heat Energy Worksheet-4

Heat Energy Worksheet-4

1. In the experiment below, when the flask was placed in hot water, the level of the drop of ink dropped and then rose because the ____ expanded first, followed by the expansion of ____

(a) Flask; air in the flask

(b) Air in the flask; flask

(c) Water; air in the flask

(d) Air in the flask; water

2. Telephone wires are always hung loosely between two poles to allow for _______

(a) Messages to be sent

(b) The flow of electricity

(c) Expansion and contraction

(d) Lightning to travel to the ground

3. Paperpins are stuck to a metal rod with wax and a lighted candle is put below the rod as shown in the diagram below:

What does this show the above experiment?

(a) Wax melts easily

(b) The candle flame conducts heat

(c) The thumbtacks expand when heated

(d) Heat travels from a hot place to a cold place

4. We wear woolen clothes in winter because :

(a) woolen clothes are warm clothes

(b) they contain trapped air which acts as an insulator

(c) both

(d) none

5. The phenomenon due to which particles of a medium actually move to the source of heat is called:

(a) radiation                                  (b) conduction

(c) Convection                               (d) none of these

6. When dried leaves are burnt the energy which changes into heat energy is :

(a) wood energy                            (b) chemical energy

(c) biological energy                    (d) none of these

7. Combustion is said to take place when a substance burns in ____ with the release of large amount of heat energy.

(a) air                                              (b) oxygen

(c) air or oxygen                           (d) none of these

8. The food which we eat has chemical energy. When this food gets digested in our body, the chemical energy changes into :

(a) mechanical energy                (b) Biological energy

(c) heat energy                              (d) none of these

9. In an electric bulb the kinetic energy of a moving electron changes first into :

(a) potential energy and then heat energy

(b) light energy and then heat energy

(c) heat energy and then light energy

(d) none of these

10. Liquid thermometer is based upon the principle of heat transfer through

(a) Conduction                             (b) Radiation

(c) Expansion of liquid               (d) None of these

Answer Key:

1. (a)
2. (c)
3. (d)
4. (b)
5. (c)
6. (b)
7. (c)
8. (c)
9. (c)
10. (c)