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 physics heat energy transfers heat and heat transfer heat energy transfer transfer of heat

Two layers of cloth of equal thickness provide warmer covering than a single layer of cloth of double the thickness, because they :

  1. behave like a thermos

  2. have lesser thickness

  3. allow heat from atmosphere to the body

  4. enclose between them a layer of air
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Air is a bad conductor of heat, hence if layer of air is isolated between two layers of cloth, warmer covering will be provided than if only one layer of cloth, where only body is isolated from surrounding air by cloth. 

Multiple choice physics heat energy transfers heat and heat transfer heat energy transfer transfer of heat

A hetaed smooth metallic body is allowed to cool in air. Which of the following statements about its heat loss is incorrect?

  1. Convection currents in the air aid the process of heat loss.

  2. Conduction is the main mode of heta loss as the body is a good conductor of heat

  3. The rate of heat loss by thermal radiation is increased due to its metallic surface.

  4. The rate of heat loss decreases as the temperature of teh body nears room temperature
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The statement that the rate of heat loss by radiation is increased due to a metallic surface is incorrect because metallic surfaces (especially smooth ones) have low emissivity, which reduces radiative heat loss. Convection and conduction are standard modes of heat transfer, and heat loss rate naturally decreases as the body approaches ambient temperature.

Multiple choice physics heat energy transfers heat and heat transfer heat energy transfer transfer of heat

A sphere, a cube and a thin circular plate, all of same material and same mass, are initially heated to same high temperature. Choose the correct statement.

  1. The plate will cool fastest and cube the slowest

  2. The sphere will cool faster and cube and the slowest

  3. The plate will cool faster and sphere the slowest

  4. The cube will cool fastest and plate the slowest.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Cooling rate is proportional to the surface area to volume ratio (A/V). For a fixed mass and material, the object with the largest surface area will have the highest rate of heat loss. A thin circular plate has the highest surface area, while a sphere has the lowest surface area for a given volume.

Multiple choice physics heat energy transfers heat and heat transfer heat energy transfer transfer of heat

Read the given statements and select the correct option.
Statement 1: An iron ball at ${35}^{o}C$ is dropped in a mug containing water at $305.15K$. Then the heat will flow from the water to the iron ball.
Statement 2: In convection, heated molecules of a liquid themselves move to carry heat from the hot region to the cold region.

  1. Both statement 1 and 2 are true and statement 2 is the correct explanation of statement 1

  2. Both statement 1 and 2 are true and statement 2 is not the correct explanation of statement 1

  3. Statement 1 is true but statement 2 is false

  4. Statement 1 is false and statement 2 is true
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

${35}^{o}C$ is equivalent to $(273.15+35)308.15K$. So iron ball is at higher temperature and heat will flow from iron ball to the water.

Multiple choice physics heat energy transfers heat and heat transfer heat energy transfer transfer of heat

In a room contain air , heat can go from one place to another

  1. By condition only

  2. by convection only

  3. By radiation only

  4. By all the three modes
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

In a room with air, heat transfer occurs via conduction (through the air and objects), convection (movement of air currents), and radiation (electromagnetic waves). All three modes contribute to heat transfer in this environment.

Multiple choice physics transfer of heat heat and heat transfer heat energy transfer heat energy transfers fundamentals of heat transfer conduction

When we touch a steel rod and a paper simultaneously, we feel that the rod is colder because:

  1. iron being a good conductor conducts more heat from our body

  2. paper being a good conductor conducts more heat from our body

  3. more heat flows from the iron to our body

  4. more heat flows from the paper to our body
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

When we touch a steel rod and a paper simultaneously in winter, we feel the rod is comparatively colder because steel being a good conductor of heat, heat from our hand flows to steel but there is no transfer of heat from our hand to paper as it is an insulator of heat. So we don't feel cold when we touch a paper but we do when we touch a steel rod.

Multiple choice physics transfer of heat heat and heat transfer heat energy transfer heat energy transfers fundamentals of heat transfer conduction

Which of the following is the very poor conductor of heat ?

  1. Water

  2. Metals

  3. Liquid other than water

  4. Steam
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Water is the poor conductor among all. As it is liquid and liquids generally have low heat conductivity than solids. Tighter the molecules are held, more the vibrational energy can transfer between them, heat is no more than vibrating molecules. If we talk about steam, its molecules are less tightly held. But it's important to note that we are talking here of heat conductivity not convection or radiation and contact surface area with heat source.

Multiple choice physics transfer of heat heat and heat transfer heat energy transfer heat energy transfers fundamentals of heat transfer conduction

Assertion (A): Woolen clothes keep the body warm in winter
Reason (R): Air is bad conductor of heat

  1. Both A and R are true,

  2. Both A and R are false

  3. Both A and R are true, R is correct explanation of A

  4. Both A and R are true, R is not correct explanation of A
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Woollen clothes effectively separate the body from surrounding air by entrapping a layer of air.
Since both wool and air are bad conductors of heat on varying levels, it creates separation that keeps bodies warm.

Multiple choice physics transfer of heat heat and heat transfer heat energy transfer heat energy transfers fundamentals of heat transfer conduction

Define insulator of heat.

  1. Substances through which heat can pass easily are called insulators of heat.

  2. Substances through which heat cannot pass easily are called insulators of heat.

  3. Substance which can easily freeze are called insulators of heat.

  4. Substances which cannot freeze easily are called insulators of heat.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Insulators are  through which heat cannot pass easily.