Tag: applications of heat conduction

Questions Related to applications of heat conduction

State the correct statement

  1. When we heat an object, it becomes hot

  2. When we heat an object, it expands in size

  3. When we heat an object, it changes its such such as water boils to form water vapour

  4. All of them are true


Correct Option: D
Explanation:

When we heat an object, it changes its shape, nature and it becomes hot, the temperature increases due to movement of atoms.

Bad conductor of heat is

  1. Copper

  2. Steel

  3. Silver

  4. None


Correct Option: D
Explanation:

All of them, being metals, are good conductors.

The ............ the conductor, the more rapidly does heat transfer takes place.

  1. better

  2. worse

  3. thinner

  4. thicker


Correct Option: A
Explanation:

The better the conductor, the more rapidly does heat transfer takes place .


Better conductor means more thermal conductivity; more the thermal conductivity; more rapidly the heat transfer takes place.

The reason for providing copper bottoms in steel pans is :

  1. aesthet, carly looks good

  2. that copper is better conductor than steel

  3. that copper is not a good conductor than steel

  4. None of the above 


Correct Option: B
Explanation:

Copper bottoms are provided in steel pans because copper is better conductor of heat than steel.

Thermal conductivity of copper is highest ($38600w/mK$) while that of steel is lowest ($1245w/mK$).

Four rods of same material but with different radii and lengths are used to connect two reservoirs of heat with the same temperature difference. Which one will conduct more heat

  1. r=1 cm, 1=1 cm

  2. r=1 cm, 1= 2 cm

  3. r= 1 cm, $1=\frac{1}{2}m$

  4. $r=\frac{1}{2}cm$, $1=\frac{1}{2}m$


Correct Option: C

Which of the following arrangements is correct on the basis of conductivity of materials?

  1. Silver > copper > aluminium > tungsten

  2. Silver > aluminium > copper > tungsten

  3. Copper > silver >tungsten> aluminium

  4. Silver > tungsten > copper > aluminium


Correct Option: C

What will be the conductivity of pure silicon crystal at 300 K temperature if  electron cottoer pair at this temperature is $ 1.072 \times 10^{10} /cm^3 $ and $ \mu _n = 1350 cn^2 /V-s and \mu _p = 480 cm^2/ V-s $ ?

  1. $ 3.14 \times 10^{-4} mho /cm $

  2. $ 3.14 \times 10^{-5} mho /cm $

  3. $ 3.14 \times 10^{-6} mho /cm $

  4. $ 3.14 \times 10^{3} mho /cm $


Correct Option: A

 Inorder to have a difference of $25 \,cm$ in their length at all temperatures, the lengths of iron and copper rods at $0^o C$ are $(\alpha _{iron} = 12 \times 10^{-6} {^oC}^{-1}, \alpha _{copper} = 17 \times 10^{-6} {^oC}^{-r})$

  1. $85 \,cm, 110 \,cm$

  2. $50 \,cm, 25 \,cm$

  3. $85 \,cm, 60 \,cm$

  4. $60 \,cm, 85 \,cm$


Correct Option: C

The heat capacity of a body depends on 

  1. the heat given

  2. the temperature rasied

  3. the mass of the body

  4. the material of he body.


Correct Option: C

In a steady state of thermal conduction, temperature of the ends $A$ and $B$ of a $20cm$ long rod are $100^oC$ and $0^oC$, respectively. What will be the temperature of the rod at a distance of $6cm$ from the end $A$ of the rod?

  1. $-30^oC$

  2. $70^oC$

  3. $5^oC$

  4. None of the above


Correct Option: B