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

Which of the following statements is wrong?

  1. Rough surfaces are better radiators than smooth surfaces

  2. Highly polished mirror-like surfaces are very good radiators

  3. Black surfaces are better absorbers than white ones

  4. Black surfaces are better radiators than white ones

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

Highly polished surfaces are excellent reflectors but very poor radiators (emitters) of heat. This is why the statement claiming they are 'very good radiators' is incorrect.

Multiple choice

Which of the following processes are used to minimize the loss of heat in a thermosflask? I. Conduction II. Convection III. Radiation

  1. I, II and III

  2. II and III

  3. I and II

  4. I and III
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A thermos flask uses a vacuum to prevent heat transfer by conduction and convection, as these require a medium. The silvered inner walls reflect heat back to minimize loss through radiation, effectively addressing all three modes of heat transfer. This combination allows the flask to maintain the temperature of its contents for long periods.

Multiple choice

In a vacuum flask silvering reduce the loss of heat by

  1. preventing entry of air.

  2. convection.

  3. chocking the leaking of heat.

  4. prevention of the radiation of heat.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The silvered surfaces of a vacuum flask reflect infrared radiation back into the flask or away from it, minimizing heat transfer. This is effective because shiny surfaces are poor emitters and good reflectors of thermal radiation.

Multiple choice

Which of the following statements is/are false? a. No medium is required for transfer of heat by radiation. b. The range in a laboratory thermometer is from 0 degrees to 90 degrees centigrade. c. The process of transference of heat in material bodies due to the actual movement of the particles of the medium is called convection.

  1. Only a

  2. Only a and b

  3. Only b

  4. Only b and c

  5. Only c
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The range in a laboratory thermometer is from 0 degrees to 90 degrees centigrade, is a false statement. Thus, it is the correct option. The range in a laboratory thermometer is from minus 10 degrees to 110 degrees centigrade.

Multiple choice

Which of the following is not a condition for the transfer of heat energy by conduction between two objects? a. The two objects must be in contact with one another. b. The objects must be made up of same metal, so that heat energy can transfer from one to another. c. The temperature of both the objects must be different from one another.

  1. Only a

  2. Only a and c

  3. Only b

  4. Only b and c

  5. Only c
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

 This is the correct option. The objects need not be made up of same metal, so that heat energy can transfer from one to another. 

Multiple choice

Which of the following statements is/are false? a. Convection is the fastest mode of heat transfer from a hot body to a cold body. b. Black bodies are good absorbers of radiant heat whereas white bodies are poor absorbers of radiant heat. c. Convection is not possible in a solid because the molecules of a solid are held strongly due to intermolecular forces.

  1. Only c

  2. Only a and b

  3. Only b

  4. Only b and c

  5. Only a
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

Convection is the fastest mode of heat transfer from a hot body to a cold body, is a false statement. Radiation, and not convection,  is the fastest mode of heat transfer from a hot body to a cold body. Hence, this is the correct option.

Multiple choice

Which of the following statements is/are false? a. The undersides of a cooking vessel is made black because black underside absorbs radiant heat rapidly from the fire. b. The radiant heat, a kind of electromagnetic energy, travels in space at the speed of 3 * 105 km/sec. c. The process of convection is not possible in air.

  1. Only c

  2. Only a and b

  3. Only a

  4. Only b

  5. Only b and c
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

This is the correct option, as the process of convection is not possible in air, is a false statement. The process of convection is possible in air.

Multiple choice

Why two thin shirts can keep us warmer than a single thick shirt in winter?

  1. Two thin shirts become thicker so prevent transmission of heat

  2. Air layer between two shirts works as good conductor

  3. Air layer between two shirts behaves like insulating media

  4. No radiation of heat takes place
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Air is a poor conductor of heat. By wearing two thin shirts, a layer of air is trapped between them, which acts as an insulator, preventing body heat from escaping to the environment.

Multiple choice

Which of the following statements is/are false?

a. It is the flow of heat energy into our body that makes us feel hot or warm. b. The energy transferred from one body to another body due to a temperature difference between them is called heat. c. The human sensation of touch is very reliable to find the degree of hotness or coldness of a body.

  1. Only a

  2. Only a and b

  3. Only b

  4. Only b and c

  5. Only c
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

This is the correct option as this statement is false. The human sensation of touch is not reliable in finding the degree of hotness or coldness of a body.