Heat

Q1. Fill in the blanks.

                           i.        The hotness of an object is determined by its temperature.

                          ii.        Temperature is measured in degree celsius.

                         iii.        A cold steel spoon is dipped in a cup of hot milk. It transfers heat to its other end by the process of conduction.

                         iv.        Land breeze blows during night.

                          v.        Sea breeze blows during day.

                         vi.        Dark coloured clothes are preferred during winter.

          vii.        Poor conductors are known as insulators.

Q2. True/False

                          i.        Temperature of boiling water cannot be measured by a clinical thermometer. True

                         ii.        Medium is required for transfer of heat by the process of radiation. False

                        iii.        Clothes of dark colours absorb heat better than clothes of light colours. True

                        iv.        Light coloured clothes are preferred during summer. True

                         v.        We should hold the thermometer by the bulb while holding it. False

                       vi.        The bulb of laboratory thermometer should not touch the bottom or the sides of the container. True

Q3. In which direction does the smoke go?

Ans. Smoke will go upward.

Q4. What do you mean by temperature?

Ans. A reliable measure of the hotness of an object is its temperature.

Q5. Which device is used to measure temperature?

Ans. Thermometer is used to measure temperature.

Q6. What is that silver stuff in a thermometer?

Ans. Silver stuff in a thermometer is mercury.

Q7. What is the unit of temperature as adopted by India?

Ans. India has adopted the celsius scale.

Q8. What is the normal temperature of a human being?

Ans. The normal temperature of human body is 37°C.

Q9. What is the range of a laboratory thermometer?

Ans. The range of a laboratory thermometer is generally from –10°C to 110°C.

Q10. What is the use of the kink in clinical thermometer?

Ans. It prevents mercury level from falling on its own.

Q11. How does heat flow from one object to another?

Ans. Heat flows from a hotter object to a colder object.

Q12. Does transfer of heat by radiation require any medium?

Ans. The transfer of heat by radiation does not require any medium.

Q13. Do all hot bodies radiate heat?

Ans. Yes, all hot bodies radiate heat.

Q14. How does heat transfer in liquids and gases?

Ans. In liquids and gases the heat is transferred by convection.

Q15. Will heat transfer if the temperature of two objects is the same?

Ans. Heat will not be transferred if the temperature of two objects is the same.

Q16. What should be the level of mercury in the clinical thermometer before use?

Ans. Mercury level should be below 35°C.

Q17. How does heat transfer in solids?

Ans. In solids, generally, the heat is transferred by the process of conduction.

Q18. What is the best way to clean a thermometer?

Ans. Thermometer should be washed before and after use, preferably with an antiseptic solution.

Q19. What is Conduction?

Ans. The process by which heat is transferred from the hotter end to the colder end of an object is known as conduction.

Q20. What are insulators of heat?

Ans. The materials which do not allow heat to pass through them easily are insulators of heat. Example: plastic and wood.

Q21. What are conductors of heat?

Ans. The materials which allow heat to pass through them easily are conductors of heat. Example: aluminum, iron and copper.