Heat Transfer

Q.

Which is the fastest mode of heat transfer?

Q. What is the boiling point of water at sea level?

Q.

The handle of the pressure cooker and nonstick vessels are made of substances like bakelite. Why?

1. They are good conductors of heat

2. They are bad conductors of heat

3. They are cheap

4. They have nice look

Q. A geyser converts electrical energy into .

1. light energy
2. mechanical energy
3. heat energy
4. chemical energy

Q. What is the energy conversion taking place in an electric heater?

1. Chemical energy is converted to heat energy
2. Heat energy is converted to electrical energy
3. Chemical energy is converted to electrical energy
4. Electrical energy is converted to heat energy.

Q.

Hot water bottles are used for fomentation. This shows that water.

Q.

Explain briefly the different modes of heat transfer.

Q.

How does heat travel in the air?

Q.

What happens when the temperature of a substance is increased?

1. Kinetic energy of the molecules of the substance increases.

2. Kinetic energy of the molecules of the substance decreases.

3. The amplitude of vibrations of molecules of the substance about their mean position decreases.

4. It does not cause any change.

Q.

Which of the following is/are the modes of heat transfer?

1. Evaporation

2. Conduction

3. Convection

4. Radiation

Q. The cool air moving towards the sea from the land is called:

1. Sea breeze
2. Land breeze
3. Moon breeze
4. Night breeze

Q. It is a rule that as we go up, the air pressure decreases.And as we know, in high temperature the air is in low pressure .But as we go up the air becomes cold not hot.So whyvis that, as we go up the air pressure decreases.

Q.

How much heat is absorbed by a 20 g granite piece as energy from the sun causes its temperature to change from 10C to 29C ( specif heat capacity of granite is 0.1 cal g-1 C-1

Q.

Boiling is a __________ phenomenon.

1. bulk

2. dynamic surface

3. atmospheric

4. surface

Q. One litre of water at 30 ⁰C is mixed with one litre of water at 50 ⁰C. The temperature of mixture will be ______________.

1. 20 ⁰C
2. 80 ⁰C
3. More than 50 ⁰C but less than 80 ⁰C
4. Between 30 ⁰C and 50 ⁰C

Q. State two phenomena from your surroundings which involve the transformation of heat energy.

Q. Which of the following statements are true about light and dark coloured clothes?

1. Dark coloured clothes are preferred during summer.
2. Light coloured clothes are preferred during summer.
3. Dark coloured clothes are preferred during winter.
4. Light coloured clothes are preferred during winter.

Q.

___________ is the state of matter in which the constituent molecules are the most loosely packed.

Q. Identify the mode of heat transfer as labelled in the image below.

1. A-Convection, B-Conduction, C-Radiation
2. A-Conduction, B-Convection, C-Radiation
3. A-Radiation, B-Conduction, C-Convection
4. A-Radiation, B-Convection, C-Conduction

Q.

Give reason: Cooking pots are provided with wooden or plastic handles.

Q. Assertion: Sea breeze occurs during the day.
Reason: During the day, the land heats up faster.

1. Both assertion and reason are true and the reason is not the correct explanation of the assertion.
2. Both assertion and reason are true and the reason is the correct explanation of the assertion.
3. Assertion is a true statement but the reason is false.
4. Both assertion and reason are false statements.

Q.

Transfer of heat by _________is faster than conduction.

Q.

Conduction is the slowest process among conduction, convection and radiation.

1. True
2. False

Q. State the direction of heat transfer by way of convection.

Q.

Question 12. Why is it so that if you wear two thin sweaters, you will feel warmer as compared to a single thick sweater?

Q. Which of these is true about the direction of heat flow?

1. Heat flows from a cold body to a hot body.
2. Heat flows from a hot body to a cold body.
3. Heat flows from a greater height to a lower height.
4. Heat flows in a random manner.

Q.

Heat always flows from a cold body to a hot body.

1. True
2. False

Q. What will happen when the copper ball at 50°C is dropped in a bucket containing water at 50°C?

1. Heat will flow from copper ball to water.
2. Heat will flow from water to copper ball.
3. Temeprature of copper ball and water increases.
4. There will be no heat flow.

Q.

A paper cup full of hot soup lying on a table is which mode of transfer of heat

Q.

Change in temperature of the body depends upon ________ and _________.