Physics · Science General

Heat Transfer Mechanisms

828 Questions

Heat Transfer Mechanisms deal with the movement of thermal energy through conduction, convection, and radiation. It involves practical applications like ocean heat storage and atmospheric heating. These fundamental physics concepts are frequently asked in general science sections.

Thermal conductionHeat convectionThermal radiationSpecific heatStates of matter

Heat Transfer Mechanisms Questions

Multiple choice physics temperature and heat heat and heat transfer transfer of heat fundamentals of heat transfer

Why do insulators take larger time to heat up?

  1. They need more heat per every degree Celsius rise in temperature.

  2. They need more energy per every degree Celsius rise in temperature.

  3. They need more to perform more work per every degree Celsius rise in temperature.

  4. They need more heat per every degree Farenheit rise in temperature.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Substances which don't allow heat to easily pass through them are known as insulators. Insulators have crystal structure of molecules, molecules are far from each other, compared to conductors. Hence, they cannot pass the heat easily through them, besides this insulators don't have free electrons to pass heat more quickly. Therefore, unit mass of an insulator requires more heat to raise its temperature by $1^{o}$ i.e. specific heat capacity of insulators is very high or we can say they need more heat per degree rise in temperature.

Multiple choice physics temperature and heat heat and heat transfer transfer of heat fundamentals of heat transfer

If needle is burnt then the heat transfer through the whole length of needle is faster because:

  1. needle is a bad conductor of heat

  2. needle is a good conductor of heat

  3. needle is an insulator

  4. none of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

If needle is burnt then the heat transfer through the whole length of needle is faster, because needle (metal), being a good conductor of heat, heat passes along the whole length by conduction, in which heat is transferred by one atom to another connected atom quickly. 

Multiple choice physics energy production perfectly black body black-body radiation black body radiation

Read the following statements carefully
(A) Black body radiation is white
(B) Emissivity of a body is equal to its absorptive power
Mark correct option:

  1. Statement (A) is correct

  2. Statement (B) is correct

  3. Both are correct

  4. Both are wrong
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
  • (A) The combination of radiation of all the visible wavelengths makes white light. Hence black  body radiation is white

(B) Emissivity of body is equal to it's absorptive power, it is not less then absorptive power or greater than absorptive power
  • Hence both the statements are true
  • Hence option C is the right answer
           

Multiple choice physics energy production perfectly black body black-body radiation black body radiation

An ideal black body is a :

  1. lump of charcoal heated to a high temperature

  2. metal coated with a black dye

  3. glass surface coated with coal tar

  4. hollow enclosure blackened inside and having a small hole
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Hollow enclosure blackened inside and having a small hole is a very good example of a black body.
Suppose once light enters inside it.
It may be absorbed or it may be reflected.
Since it is blackened from inside, there is a high probability that it will be absorbed.
Now if it is reflected, it will suffer multiple reflections and it is very unlikely that it will come out of the hole because the aperture of hole is too small. Moreover, with each reflection, more and more fraction of it will be absorbed. So, it will serve as a good black body.

Multiple choice physics energy production perfectly black body black-body radiation black body radiation

An ideal black body at room temperature is thrown in a furnace. It is observed that

  1. initially it is darkest body and at later time the brightest

  2. it is darkest body at all the times

  3. it cannot be distinguished at all the times

  4. initially it is the darkest body and at later times it cannot be distinguished
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Initially the black body is in bright environment. So, it appears dark and finally when its temperature becomes equal to temperature of furnace, it becomes invisible

Multiple choice physics energy production perfectly black body black-body radiation black body radiation

Radiation coming from the hole of a Ferry's Black body is called 

  1. black radiation.

  2. cavity radiation.

  3. Ferry's radiation.

  4. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
$\rightarrow$ Radiation coming from the hole of ferry's black body is called cavity radiation because this black body is double walled evacuated spherical cavity whose inner wall is blackened

Multiple choice

As a sample of matter is heated, its particles?

  1. stop moving

  2. move more slowly

  3. move more quickly

  4. are unaffected
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Temperature is a measure of the average kinetic energy of particles. As matter is heated, particles gain kinetic energy and move more quickly.

Multiple choice

energy of motion

  1. potential energy

  2. kinetic energy

  3. heat energy

  4. freezing
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Kinetic energy is defined as the energy an object possesses due to its motion. Potential energy is stored energy, and heat is energy transfer.