Tag: temperature and heat

Questions Related to temperature and heat

Conduction of heat is possible:

physics temperature and heat modes of heat transfer - conduction conduction heat and modes of heat transfer

  1. when the bodies are apart from each other

  2. when the bodies have same temperature and in thermal contact

  3. when they have different temperatures maintaining distance between them

  4. bodies should be in contact and should have different temperatures

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Correct Option: D
Explanation:

Conduction is only possible when the bodies in contact have a temperature difference.

More energetic molecules of a body transfer some of their energy to other molecules, without any change in their position in:

physics temperature and heat modes of heat transfer - conduction conduction heat and modes of heat transfer

  1. conduction

  2. convection

  3. radiation

  4. none of these

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Correct Option: A
Explanation:

Conduction is defined as the process of transferring heat from molecule to molecule, without the actual movement of molecules.

Here, more energetic molecules of a body transfer some of their energy to other molecules, without any change in their position.

The thermal conductivity of the plate depends upon

physics temperature and heat modes of heat transfer - conduction conduction heat and modes of heat transfer

  1. the temperature difference between the two sides

  2. the thickness of the plate

  3. the area of the plate

  4. nature of the material

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Correct Option: D
Explanation:

Thermal conductivity of any object depends solely on the material of the object.
It is an intrinsic property and is independent on dimensions/mass/etc of the body.
For example, all iron rods will have same thermal conductivity.
All copper rods will have same thermal conductivity.
But, thermal conductivity of iron rod will be different from that of copper rod.

Which of the following qualities are best suited for handling a cooking utensil?

physics temperature and heat modes of heat transfer - conduction conduction heat and modes of heat transfer

  1. high specific heat and low thermal conductivity

  2. high specific heat and high thermal conductivity

  3. low specific heat and low thermal conductivity

  4. low specific heat and high thermal conductivity

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Correct Option: A
Explanation:

High specific heat means high energy required to increase temperature.
Hence for a given amount of energy, temperature would be less for high specific heat.
Low conductivity means heat is not conveyed to all portions of the conductor easily.
Hence, handling the instrument would be easy.

If pressure on a gas is increased from $P$ to $2P$, then its heat conductivity

physics temperature and heat modes of heat transfer - conduction conduction heat and modes of heat transfer

  1. increases

  2. decreases

  3. becomes zero

  4. remains unchanged

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Correct Option: D
Explanation:

Conductivity of gas does not depend on pressure.

Thermal conductivity of a metal rod depends on :

physics temperature and heat modes of heat transfer - conduction conduction heat and modes of heat transfer

  1. area of cross section

  2. temperature gradient

  3. time of flow of heat

  4. none of these

Show answer
Correct Option: D
Explanation:

Thermal conductivity is characteristic to the material and doesn't depend on any of the factors given.
In fact, heat flow depends on the factors given in options list.

Conduction is:

physics temperature and heat modes of heat transfer - conduction conduction heat and modes of heat transfer

  1. the process of transfer of heat which does not require any material medium

  2. the process of transferring heat from molecule to molecule, without the actual movement of molecules

  3. the process in which molecules conduct heat by moving from hotter regions to colder regions

  4. the process in which heat energy moves through the medium of protons

Show answer
Correct Option: B
Explanation:

Conduction is defined as the process of transferring heat from molecule to molecule, without the actual movement of molecules.

The coefficient of thermal conductivity of a metallic rod does not depend upon :

physics temperature and heat modes of heat transfer - conduction conduction heat and modes of heat transfer

  1. the length of the rod

  2. the cross-sectional area of the rod

  3. the temperature difference between the ends of the rod

  4. the nature of the metal

Show answer
Correct Option: A,B,C
Explanation:

Coefficient of $Thermal$ $Conductivity$ is the internal property of the metal and is independent of all the $external$ properties of the material.

So Coefficient of $Thermal$ $Conductivity$ is independent of dimensions, temperatures and other external factors too. It only depend on nature of material.

Conduction is ,

physics temperature and heat modes of heat transfer - conduction conduction heat and modes of heat transfer

  1. the process of transfer of heat which does not require any material medium

  2. the process of transferring heat from molecule to molecule, with out any movement of molecules

  3. the process in which molecules conduct heat by moving from hotter regions to colder regions

  4. the process in which heat energy moves through the medium of protons

Show answer
Correct Option: B
Explanation:

Conduction is the process by which heat or electricity is directly transmitted through the material of a substance without movement of the material.

It is warmer to have two thin blankets than to have single thick blanket because:

physics temperature and heat modes of heat transfer - conduction conduction heat and modes of heat transfer

  1. Thick blankets cannot give more warmth

  2. Two blankets allow more heat to pass through them

  3. Air between the two blankets is a good conductor of heat

  4. Air between the thin blankets does not allow heat to pass through it since it is a bad conductor

Show answer
Correct Option: D
Explanation:

Air is bad conductor of heat, so it does not allow the heat to pass through, while the single thick blanket is a better conductor of heat so it is less effective.