Class 7 Heat and its Effect

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Heat and its Effect

Multiple-choice Questions:

  1. In liquids, heat transfer takes place by

(a) radiation

(b) conduction

(c) convection

(d) none of these

  1. Some stainless steel frying pans are provided with copper bottoms. The reason for this could be that:

(a) copper bottom makes the pan more durable

(b) such pan appears colourful

(c) copper is a better conductor of heat than stainless steel

(d) none of these

  1. Transfer of heat by conduction process takes place in

(a) liquids only

(b) solids only

(c) gases only

(d) All of these.

  1. Heat energy from the sun reaches us by the process

(a) conduction

(b) convection

(c) radiation

(d) both a and b.

5.The woollen clothes keep us warm during winter because

A) wool is an insulator

B) wool is a conductor

C) wool traps air

D) wool has a vacuum.

(a) A and B

(b) B and C

(c) C and D

(d) A and C

  1. The transfer of heat by convection takes place in:

(a) Solids and liquids

(b) Solids and vacuum

(c) Gases and liquids

(d) Vacuum and gases

  1. The process which can transfer heat through the vacuum, as well as air, is:

(a) conduction

(b) convection

(c) irradiation

(d) radiation

Ans.

  1. (c) convection
  2. (c) copper is a better conductor of heat than stainless steel
  3. (b) solids only
  4. (c) radiation
  5. (a) A and B
  6. (c) Gases and liquids
  7. (d) radiation

 Fill in the blanks:

1.———- flows from a region of higher temperature to a region of lower temperature.

2.—–—– thermometer is used to measure our body temperature.

  1. Air is a————- conductor of heat.
  2. Shining and smooth surfaces are better ————-of heat.
  3. No medium is required for the transfer of heat by the process of————————-.

Ans.

 1. Heat

2. Clinical

3. bad

4. better reflectors

5. radiation

Very short Answer Question.

  1. State the unit in which temperature is commonly measured.

Ans. There are three units which are commonly used to measure the temperature: Degree Celsius, Fahrenheit and Kelvin.

  1. What is the usual temperature range of a laboratory thermometer?

Ans. A common laboratory thermometer can measure temperature from 10°C to 110°C.

This is called the range of a laboratory thermometer.

  1. What are the three methods of transfer of heat?

Ans. The three methods of transfer of heat are:

  • By conduction method of transfer of heat
  • By convection method of transfer of heat
  • By radiation method of transfer of heat
  1. When one end of an Iron rod is heated its other end also becomes hot soon. Name the process by which heat flows in the rod?

Ans. By conduction method.

  1. What is the other name of poor conductors of heat?

Ans. Bad conductors of heat or Insulators.

  1. Name the two types of breeze which blow in coastal areas

Ans. land breeze and sea breeze

  1. Which method of heat transfer does not require any medium?

 Ans. Radiation method of heat transfer does not require any medium

  1. A person sitting in front of a room heater feels hot. Name the process by which heat is transferred.

Ans. By convection method of heat transfer.

 



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