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Lakhmir Singh Science Chapter 4 Heat Class 7

Last updated on October 4th, 2022 at 12:23 am

When The Temperature Is Same

What is the other name for poor conductors of heat?

Insulators

The process by which heat is transferred within a liquid (or gas).

Convection

Explain whether water is a good conductor of heat or a good convector of heat.

Water Is a Good Convector of Heat

Name the process by which heat is transferred by the movement of a liquid (or gas).

Convection

Name the process by which:

  • water in a beaker gets heated by the burner kept below it.
  • air above the candle flame gets heated.

Convection Is the Answer for Both

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

Land Breeze and Sea Breeze

Which of the following method of heat transfer will work in empty space (or vacuum)?

Convection, Radiation, Conduction

Radiation

Name a method of heat transfer which does not require a material medium.

Radiation

State the method by which heat is transferred:

  1. from the sun to the earth.
  2. from a man’s hand when placed on a cold iron vessel
  3. from the bottom of a hot liquid to its upper cooler parts.
  1. Radiation
  2. Conduction
  3. Convection

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

Radiation

How does the heat from the sun reach the earth?

By Radiation

When we stand next to a burning fire, we can feel the heat on our face. Name the process which transfers this heat from fire.

Radiation

A hot utensil (filled with hot water) kept away from flame cools down by transferring heat to surroundings. Name the process of heat transfer involved.

Conduction

Which of the following is a better reflector of heat and which one is a better absorber of heat?

(a) Shiny white surface (b) Dull black surface

A-Better Reflector of Heat

B – Better Absorber of Heat

Short Answer Type Questions

  1. Why is a frying pan made of metal (like aluminum or stainless steel) but the handle of frying pan is made of plastic (or wood)?

Plastic or wood are poor conductors of heat and can be lifted safely from their handle.

  1. Why are cooking utensils provided with handles made of plastic (or wood) ?

Cooking pots have wooden or plastic handles because they conduct heat poorly. This keeps the heat from the pan from transferring to our hand. As a result, we can hold the utensils comfortably in our hands.

  1. Explain why, a laboratory thermometer is not suitable for measuring human body temperature.

A laboratory thermometer cannot be used to measure the temperature of a human body because its range is wide, ranging from –10°C to 110°C, whereas the normal body temperature in humans is only 37°C.

  1. Why does the mercury level not fall on its own when the bulb of a clinical thermometer is removed from the mouth ?

Because of the kink, the mercury in a clinical thermometer does not fall or rise when removed from the mouth. It keeps the mercury level from dropping on its own.

  1. Define conduction. Give one example where heat is transferred by the process of conduction.

Conduction is the transfer of heat from one medium to another through physical contact between the two mediums. Example heat transferred between gas and pan while making food.

Note :- We only provide question and answers of the book which will help in kids home work and school exams.

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