Tag: transfer of heat

Questions Related to transfer of heat

Which of the following are good conductors of heat?

physics transfer of heat heat and heat transfer heat energy transfer heat energy transfers fundamentals of heat transfer conduction

  1. Metals

  2. Glass

  3. Water

  4. Wood

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Correct Option: A
Explanation:

Metals are generally good conductors of heat.
Non - metals are poor conductors of heat.

Which of the following is the very poor conductor of heat ?

physics transfer of heat heat and heat transfer heat energy transfer heat energy transfers fundamentals of heat transfer conduction

  1. Water

  2. Metals

  3. Liquid other than water

  4. Steam

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Correct Option: A
Explanation:

Water is the poor conductor among all. As it is liquid and liquids generally have low heat conductivity than solids. Tighter the molecules are held, more the vibrational energy can transfer between them, heat is no more than vibrating molecules. If we talk about steam, its molecules are less tightly held. But it's important to note that we are talking here of heat conductivity not convection or radiation and contact surface area with heat source.

Assertion (A): Woolen clothes keep the body warm in winter
Reason (R): Air is bad conductor of heat

physics transfer of heat heat and heat transfer heat energy transfer heat energy transfers fundamentals of heat transfer conduction

  1. Both A and R are true,

  2. Both A and R are false

  3. Both A and R are true, R is correct explanation of A

  4. Both A and R are true, R is not correct explanation of A

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Correct Option: C
Explanation:

Woollen clothes effectively separate the body from surrounding air by entrapping a layer of air.
Since both wool and air are bad conductors of heat on varying levels, it creates separation that keeps bodies warm.

Substances which allow heat to pass through them are called:

physics transfer of heat heat and heat transfer heat energy transfer heat energy transfers fundamentals of heat transfer conduction

  1. Conductors

  2. Insulators

  3. Moderators

  4. None of these

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Correct Option: A
Explanation:

Conductors allow heat to pass through them through vibration of the molecules.

A coin is dipped in the molten wax in a glass tube. When we heat the upper part of the glass tube, the wax around the coil will not melt because:

physics transfer of heat heat and heat transfer heat energy transfer heat energy transfers fundamentals of heat transfer conduction

  1. Wax has a very high melting point

  2. Wax is a good conductor of heat

  3. Glass is a good conductor of heat

  4. Wax or glass are bad conductors

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Correct Option: D
Explanation:

Glass is a bad conductor of heat hence the heat from the upper part of the glass tube will not transfer easily to the lower part. Having said that, even wax is a bad conductor of heat and won't melt easily. 

Mercury is a good conductor of heat.State true or false.

physics transfer of heat heat and heat transfer heat energy transfer heat energy transfers fundamentals of heat transfer conduction

  1. True

  2. False

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Correct Option: A
Explanation:
Mercury is good conductor of heat. (True)
Thermal conductivity of mercury is $8.30W/mK$. This is the fact why it was used in classical, thermometers for measuring temperature.

The best conductor of heat is

physics transfer of heat heat and heat transfer heat energy transfer heat energy transfers fundamentals of heat transfer conduction

  1. Silver

  2. Bronze

  3. Aluminium

  4. Copper

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Correct Option: A
Explanation:

Silver is the best conductor of heat among the given options.

When you pour hot tea suddenly on to a glass tumbler, it cracks. Because:

physics transfer of heat heat and heat transfer heat energy transfer heat energy transfers fundamentals of heat transfer conduction

  1. Glass cannot resist heat

  2. Glass expands unevenly around the place of contact with the tea

  3. Tea has chemicals which react with glass tumblers.

  4. The reason is yet to be discovered by the scientists.

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Correct Option: B
Explanation:

When the hot tea is poured into the glass tumbler one side of the glass expands while the other side doesn't. Since glass is not a good conductor of heat, it breaks.

Cups are not made of metals. The reason is:

physics transfer of heat heat and heat transfer heat energy transfer heat energy transfers fundamentals of heat transfer conduction

  1. Metals are good conductors

  2. Metals are bad conductors

  3. Metals are expensive

  4. None of the above

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Correct Option: A
Explanation:

Metals are good conductors of heat hence a person might get his fingers injured if he holds the hot plate. 

Select the odd one out w.r.t. conduction of heat (gold, copper, mercury, cork)

physics transfer of heat heat and heat transfer heat energy transfer heat energy transfers fundamentals of heat transfer conduction

  1. cork

  2. gold

  3. copper

  4. mercury

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Correct Option: A
Explanation:

Cork is a bad conductor of heat rest are good conductors