Conduction

Q.

Question 2
Give two examples each of conductors and insulators of heat.

Q.

What are the three modes of heat transfer?

Q.

Give an example of metal which is a poor conductor of heat.

Q. Question 11
Stainless steel pans are usually provided with copper bottoms. The reason for this could be that

(a) copper bottom makes the pan more durable.
(b) such pans appear colourful.
(c) copper is a better conductor of heat than the stainless steel.
(d) copper is easier to clean than the stainless steel.

Q.

A material which allows heat to easily pass through it is termed as ______________.

1. conductor

2. non-conductor

3. insulator

4. resistor

Q.

What is the direction of heat flow?

Q.

Question 3

Explain why the bulb would not glow in the arrangement shown in Fig.

Q.

Which statement is the best example of transfer of heat energy by conduction?

1. Heat energy is transferred from the surface soil to the rocks below.

2. Heat energy is transferred from the Sun to the Earth.

3. Heat energy is transferred from the top to the bottom of a lake.

4. Heat energy is transferred from the Earth's surface to the upper atmosphere.

Q.

Which of the following is not an insulator?

1. Bricks

2. Brass

3. Bamboo

4. Plastic

Q. A steel spoon kept on a candle flame becomes hot after a while, because heat transfers from the flame to the spoon by ___________.

1. conduction
2. convection
3. (a) and (b) above.
4. radiation

Q.

Is human body an insulator of heat

Q. How can we explain all three processes of transfer of heat with thermos flask.

Q.

A container with $1kg$ of water in it is kept in sunlight, which causes the water to get warmer than the surroundings. The average energy per unit time per unit area received due to the sunlight is $700W{m}^{-2}$ and it is absorbed by the water over an effective area of $0.05m^2$. Assuming that the heat loss from the water to the surroundings is governed by Newton’s law of cooling, the difference $(in<span\; style="font-family:"Cambria"\; math",=""\; serif;mso-bidi-font-family:"cambria=""\; math";="">℃</span>)$ in the temperature of water and the surroundings after a long time will be _____________.

(Ignore the effect of the container, and take constant for Newton’s law of cooling $=0.001s^{-1}$, the Heat capacity of water $=4200Jk{g}^{-1}{K}^{-1}$)

Q. The handle of metal pan gets hot while cooking food. Which mode of heat transfer is responsible for this?

1. Radiation
2. Conduction
3. Convection
4. Vaporization

Q. How can heat travel from one body to other body

Q.

When standing barefoot in a cool room having both carpet and tiles flooring, the tile feels colder than the carpet. What can be the reason for this?

Q.

The More It Dries the Wetter It Becomes. What Is It?

Q.

How are temperature and hotness of body related?

Q.

If the temperature difference between the body and surroundings is small, then the rate of loss of heat is directly proportional to _______.

Q.

Air is a good conductor of heat.

Say True or False.

1. True

2. False

Q. What do you mean by transfer of heat? Explain the process of transfer of heat in solids, liquids and gases.

Q.

Question 13

In the arrangements A and B shown in Figure, pins P and Q are fixed to a metal loop and an iron rod with the help of wax. In which case are both the pins likely to fall at different times? Explain.

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Question 20

Look at the figure.

The length of wire PQ in case of A is equal to the diameter of the semicircle formed by the wire CDE, in case B. One pin is attached to each wire with the help of wax as shown in Figure. Which pin will fall first? Explain.

Q. Why a brass tumbler feels much cooler than a wooden tray?

Q. Does air get heated up through convection or radiation?

Q.

Rubber is an example of:

1. Electric cell

2. None of these

3. Insulator

4. Conductor

Q.

We prefer wearing dark-coloured clothes in winter.

Q.

Which of the following statement(s) are correct regarding heat?

1. Heat transfer between two bodies through conduction requires direct contact between the two bodies.

2. Heat transfer through convection is only possible in liquids and gases.

3. Heat transfer cannot occur in the absence of any physical medium between two objects.

4. Heat transfer always occur from a body at a higher temperature to a body at lower temperature.

Q.

The mode of heat transfer between earth and sun is radiation.

1. conduction

2. convection

Q. In solids, transfer of heat predominantly occurs through ______.

1. conduction
2. vaporization
3. radiation
4. convection