Tag: applications of heat conduction

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Questions Related to applications of heat conduction

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

Which of the following fabrics is preferred for winter garments ?

  1. Nylon

  2. Cotton

  3. Wool

  4. Silk
Reveal answer Fill a bubble to check yourself
C Correct answer
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.

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

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

  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
Reveal answer Fill a bubble to check yourself
D Correct answer
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.

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

How does air trapped by the woolen fabric help ?

  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.
Reveal answer Fill a bubble to check yourself
C Correct answer
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.

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

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?

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

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

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

  4. $r=2r _0;l=2l _0$
Reveal answer Fill a bubble to check yourself
B Correct answer
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.

Multiple choice evs - i transfer of heat clothes - our necessity applications of insulation uses of good and poor conductors in daily life voyages and discoveries applications of heat conduction

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.

  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
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

According to Kirchhoff's law of radiation, good absorbers are good emitters. A black spot is a better absorber than the shiny surface, so it will emit more radiation and appear brighter when the object cools in a dark room.

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

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

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
B Correct answer
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.