Physics · Science General

Heat Transfer Mechanisms

877 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 not true about infrared radiations?

  1. All hot bodies emit infrared radiations.

  2. They heat up any body that comes in their path.

  3. They are absorbed by the ozone layer.

  4. Heat from the sun is transferred in the form of infrared radiations.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

There are some properties of infrared radiations such as (i)         Heat from the sun is transferred in the form of infrared radiations. (ii)        All hot bodies emit infrared radiations. (iii)       They heat up any body that comes in their path. (iv)       One-third of sunrays is composed of infrared radiations. Thus, options (1), (2) and (4) are properties of infrared radiations. But UV rays are not infrared rays. They are not absorbed by ozone layer in the atmosphere. Therefore, option (3) is not true about infrared radiations.

Multiple choice

Why does steam cause more severe burns than boiling water?

  1. Because of latent heat of fusion

  2. Because of latent heat of sublimation

  3. Because of latent heat of vapourisation

  4. Because of latent heat of conversion
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Steam causes more severe burns than boiling water because of latent heat of vapourisation.

Multiple choice

When sand is poured over some burning material, the fire goes off. This is because

  1. pouring the sand cools the material to a temperature below its ignition temperature

  2. supply of air is cut off

  3. sand is a bad conductor of heat

  4. All of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Sand is a bad conductor of heat. Sand cuts off the supply of air. Pouring the sand cools the material to a temperature below its ignition temperature. 

Multiple choice

For the flow of viscous fluid over a flat plate, if the fluid temperature is the same as the plate temperature, the thermal boundary layer is

  1. thinner than the velocity boundary layer

  2. thicker than the velocity boundary layer

  3. of the same thickness as the velocity boundary layer

  4. not formed at all
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

For the flow of viscous fluid over a flat plate, if the fluid temperature is the same as the plate temperature, the thermal boundary layer is not formed at all because boundary layer formation takes place if there is some difference in fluid property of no slip layer and the remaining fluid. As given here, fluid is viscous and flowing over a flat plate. Here, definitely a kinematic boundary layer will be formed, but as there is no temperature difference, so no formation of thermal boundary layer.

Multiple choice

As the temperature increases, the thermal conductivity of a gas

  1. Increases

  2. Decreases

  3. Remains constant

  4. Increases up to a certain temperature and then decreases
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Correct option is (1). The kinematic theory of gases predicts & the experiment confirms that the thermal conductivity of gases is proportional to the square root of thermodynamic temperature. thermal conductivity of gases$\alpha$ $(temperature)^{\frac{1}{2}}$ as temp  $\uparrow$        Conductivity of gas $\uparrow$

Multiple choice

Heat and work are

  1. intensive properties

  2. extensive properties

  3. point functions

  4. path functions
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Multiple choice physics electric current and its effects coil and fuse heating effect of electric current- uses applications of heating effect of electric current

From below which are the applications of heating effect of electric current?

  1. Electric immersion water heater

  2. Electric Iron Box

  3. Electric Fuse

  4. All of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

According to heating effect of electric current, heat is produced in the materials that have resistance, thus electric immersion water heater, electric iron box and electric fuse are the applications of heating effect of electric current.

Multiple choice physics transfer of heat applications of heat conduction applications of insulation clothes - our necessity

The molecules of medium vibrate about their mean positions during heat transfer in the process of

  1. Conduction

  2. Radiation

  3. Convection

  4. None
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The molecules of medium transfer heat as they vibrate about mean position in conduction.
The molecules of medium absorb heat, they rise and other molecules of medium come to take their place convection
In radiation, medium does not play role.