Heat Flow

Q.

What are convection current? Give examples.

Q.

What happens in convection mode of heat transfer?

Q.

What are convection, conduction, and radiation?

Q.

Which natural phenomenon causes land and sea breeze.

Q. Kinetic energy is:

1. Directly proportional to temperature
2. Directly proportional to heat
3. Directly proportional to friction
4. Inversely proportional to temperature

Q. Why is it advisable to wear light coloured clothes during summer?

1. They absorb less heat.
2. They absorb more heat.
3. They are cheaper.
4. They are more beautiful to the eyes.

Q.

Ventilators are provided at the top of the room

1. To bring oxygen for breathing

2. So that sunlight may enter the room

3. To maintain convectional currents to keep the air fresh in the room

4. To provide an outlet for carbon dioxide

Q. The initial temperatures of two bodies B and C were $T_1$ and $T_2$ respectively. They are brought into contact and heat starts flowing from C to B until their temperature reaches $T$. Which of the following is true?

1. $T<T_1<T_2$
2. $T_1<T<T_2$
3. $T_2<T_1<T$
4. $T_2<T<T_1$

Q. Two objects A and B of the same temperature are connected through a pipe. The system is said to be in thermal equilibrium, since there is no heat transfer between them.

1. True

2. False

Q. If there is no transfer of energy taking place between two objects, then ___.

1. they are at different temperature
2. they are at the same temperature
3. they are at very high temperature
4. they are at very low temperature

Q.

Suppose you have three bodies A, B and C. A and B are at same temperature. When B and C are brought in contact, heat flows from C to B until they are at same temperature. What will happen when A and C are brought in contact?

1. Heat will flow from A to C.

2. Heat will flow from C to A.

3. Insufficient information

4. Heat will not flow.

Q.

Shining or white bodies are ___________ absorbers of radiant heat.

Q.

The direction of heat flow takes place from hot area to a cold area.

1. True

2. False

Q.

Two metallic objects A and B are brought in contact with each other but no heat transfer occurs between them. What could be the possible reason for this?

1. Temperature of A > Temperature of B

2. Temperature of B > Temperature of A

3. Can't be determined

4. Temperature of A = Temperature of B

Q.

State whether the land cools at a slower or faster rate than water. Give a reason in support of your answer.

Q.

Explain some practical applications of convection.

Q.

Differentiate between convection and radiation.

Q.

Heat flows from an object of ____ temperature to an object of ____ temperature.

1. some, same

2. higher, lower

3. lower, higher

4. higher, even higher

Q.

The direction of heat transfer depends on ___ of the bodies.

Q.

Fill in the blanks with suitable words:

Wood charcoal is a ……….conductor of heat and electricity.

Q.

Which of the following is a bad conductor of heat?

1. Aluminium

2. Zinc

3. Wood

4. Copper

Q.

Which of the following statement is correct?

1. All the above

2. All substances expand on heating

3. Heat energy flows from hot body to the cold body

4. All substances contract on cooling

Q.

In which direction does heat flow?

1. From a hot area to a cold area

2. From a cold area to a hot area

3. Heat is a stationary phenomenon

4. Heat flows in a random manner

Q. Suppose a body A at a higher temperature is brought into contact with another body B at a lower temperature, then which among the following are true?

1. Molecules of body A becomes less active.
2. The heat flow is from body A to body B.
3. Molecules of body A becomes more active.
4. The heat flow is from body B to body A.