# Lakhmir Singh Science Class 7 Chapter 4 – Heat

## Lakhmir Singh Science Class 7 – Heat

Name of Author – Lakhmir Singh And Manjit Singh

Subject – Science / Board – CBSE /ICSE

Lakhmir Singh Science Class 7 Chapter 4 – Heat for CBSE/ICSE Students

Give the unit in which temperature is commonly measured.

Degree Celsius

On a Celsius scale, what is the normal body temperature?

37 Degree Celsius

What is the normal temperature range of a laboratory thermometer?

-10 To 100 Degree Celsius

A thermometer is typically made from a liquid.

Mercury

What prevents the mercury level in the glass tube of a clinical thermometer from falling on its own when its bulb is removed from the mouth of a patient?

Kink

Which thermometer has a temperature range of (a) -10°C to 110°C? (b) between 35°C and 42°C?

A-Clinical Thermometer

B-Laboratory Thermometer

On the glass tube of a clinical thermometer are usually two temperature scales. Name these two temperature scales.

Celsius Scale, Farenheight Scale

What is the Fahrenheit range of a clinical thermometer?

94 Degree to 108 Degree Fare height

On a Fahrenheit scale, what is the normal body temperature?

98.6

What is the name of those thermometers that do not use mercury?

Laboratory Thermometer

Identify the thermometer that can automatically record the highest and lowest temperatures for the entire day.

Laboratory Thermometer

There are three ways in which heat can flow (or be transferred).

By Conduction, By Convection and by Radiation

As soon as one end of an iron rod is heated, the other end also becomes hot. Name the process by which heat is transferred in the iron rod.

By Conduction

The process by which a frying pan transfers heat from a gas stove to the food it contains through its bottom.

Conduction

When does the flow of heat from a hot object to a cold object stop?

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)?

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

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.
2. Conduction
3. Convection

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

How does the heat from the sun reach the earth?

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.

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

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.

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