Tag: applications of heat conduction

Questions Related to applications of heat conduction

Which of the following fabrics is preferred for winter garments ?

physics transfer of heat applications of heat conduction applications of insulation clothes - our necessity

  1. Nylon

  2. Cotton

  3. Wool

  4. Silk

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Correct Option: C
Explanation:

Wool is the fabric that is preferred for winter garments. As wool is bad conductor of heat. It insulates the body from the surrounding. And the air which is trapped in between the wool fibers; it prevents the flow of heat from our body to cool surrounding.

Which of the following is not a reason for using woolen clothes in Winter ?

physics transfer of heat applications of heat conduction applications of insulation clothes - our necessity

  1. Wool is an insulator of heat.

  2. It traps a layer of air in its fabric.

  3. Air being an insulator doesn't allow body heat to escape into the atmosphere.

  4. All the above

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Correct Option: D
Explanation:

Reason behind using woolen clothes during winter is that wool is the bad conductor of heat, it insulates the body from the surrounding. And the air which is trapped between woolen fabrics, prevents the flow of heat from the body as air is a bad conductor of heat too. So as a result the heat present in the body remains trapped in the body, it can't escape to atmosphere.

How does air trapped by the woolen fabric help ?

physics transfer of heat applications of heat conduction applications of insulation clothes - our necessity

  1. Air is a good conductor of heat and allows warm air to come near body

  2. Air is a bad conductor of heat and allows body heat to escape into atmosphere

  3. Air is a bad conductor of heat and doesn't allow body heat to escape into atmosphere

  4. Air is a good conductor of heat and doesn't allow cool air to come near body.

Show answer
Correct Option: C
Explanation:

Air trapped by the woolen fabric help us during winter. As air is bad conductor of heat and doesn't allow body heat to escape into atmosphere. The heat stored inside the body does not goes out as wool and air acts as a layer of insulator. And body heat is not escaped from the body.

When a metal conductor connected to left gap of a meter bridge is heated, the balancing point.

physics transfer of heat applications of heat conduction applications of insulation clothes - our necessity

  1. Shifts towards right

  2. Shifts towards left

  3. Remains unchanged

  4. Remains at zero

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Correct Option: A
Explanation:

When resistor is heated its resistance increases hence the balancing point will shift towards right.

Which of the following circular rods (given radius r and length l), each made of the same material and whose ends are maintained at the same temperature will conduct most heat?

physics transfer of heat applications of heat conduction applications of insulation clothes - our necessity

  1. $r=r _0;l=l _0$

  2. $r=2r _0;l=l _0$

  3. $r=r _0;l=2l _0$

  4. $r=2r _0;l=2l _0$

Show answer
Correct Option: B
Explanation:

Heat is given by $H=KA\Delta \theta _x=K\pi r^2 \dfrac{\Delta \theta} {l}$

For option B the value of $H$ will be more.

A shining metallic ball with a small black spot on its surface is heated to very high temperature and then quickly taken to a dark room. Then.

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  1. Both appear equally bright

  2. The spot appears brighter than the ball

  3. The spot appears darker than the ball

  4. Both are invisible in the dark room

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Correct Option: B

If object A and object B has no transfer of heat, then they both are in

physics temperature and heat applications of heat conduction applications of insulation clothes - our necessity

  1. Catalytic

  2. Thermal equilibrium

  3. Expansion

  4. None

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Correct Option: B
Explanation:

$Object \ A \rightleftharpoons Object\ B$
Both are at same temperature or there is not temperature difference between them.

Good conductor of heat is

physics temperature and heat applications of heat conduction applications of insulation clothes - our necessity

  1. Hydrogen

  2. Oxygen

  3. Nitrogen

  4. None

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Correct Option: D
Explanation:

All of them are gases, which are not good conductors of heat.

Air is a _______ conductor of electricity.

physics temperature and heat applications of heat conduction applications of insulation clothes - our necessity

  1. Good

  2. Bad

  3. Both

  4. None

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Correct Option: B
Explanation:

All gases are poor conductor of heat. Air is a very poor conductor of heat.

Air is a good conductor of heat. True or false.

physics temperature and heat applications of heat conduction applications of insulation clothes - our necessity

  1. True

  2. False

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Correct Option: B
Explanation:
False
Air is bad conductor of heat. It is due to the air trapped between the cotton molecules which gives warmth on taking quilt in winter It is due to air molecules trapped between wool fabrics which provide warmth to body during winter season.