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 electric current and its effects thermal effect of electric current heating effect of electric current effect of electric current

The amount of heat produced in a wire depends on its material-

  1. Length

  2. Thickness

  3. Length and thickness

  4. None of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Amount of heat produced in wire = $I^2R$

Where $R$ = Resistance of wire
            $I$ = Current through wire
As resistance of wire   $R \propto   \dfrac{L}{A}$
So heat produced depends on Length as well as thickness.        

Multiple choice physics electric current and its effects thermal effect of electric current heating effect of electric current effect of electric current

When a current flows through a conductor its temperature

  1. May increase or decrease

  2. Remains same

  3. Decreases

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

According to Joule's heating effect of current, heat energy is generated across a conductor due to the current flowing through it and hence its temperature increases.

Multiple choice physics electric current and its effects thermal effect of electric current heating effect of electric current effect of electric current

Heating effect of current is due to

  1. flow of voltage through the conductor.

  2. flow of current through a conductor.

  3. both A and B.

  4. neither A nor B.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Whenever an electric current is passed through a conductor, it gets heated up. And the amount of heat created is directly proportional to the square of the current.

Multiple choice physics electric current and its effects thermal effect of electric current heating effect of electric current effect of electric current

Whenever an electric current is passed through a conductor,it gets heated up.this means that a part of electrical energy, given to the conductor, gets converted to

  1. potential energy

  2. gravitational energy

  3. heat energy

  4. none of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Whenever an electric current is passed through a conductor,it gets heated up. This indicates that a part of electrical energy gets converted into heat energy.

Multiple choice physics electric current and its effects thermal effect of electric current heating effect of electric current effect of electric current

An electric heater kept in vacuum is heated continuously by passing electric current. Its temperature:

  1. will go on rising with time

  2. will stop after sometime as it will loose heat to the surroundings by conduction

  3. will rise for sometime and thereafter will starts falling

  4. will become constant after sometime because of loss of heat due to radiation
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Treating initially that there is no radiation and on applying voltage to the heater, the temperature of the heater rises. As the temperature rises, the radiation also increases.
As the input power($i^2r$) is constant, the output power should also be constant.
Initially temperature will be increasing and  radiation as well. When the heater reaches a certain temperature, the radiation power equals the input power and the temperature of the heater stops rising.
Thus temperature becomes constant after some time.  

Multiple choice physics electric current and circuit thermal effect of electric current heating effect of electric current electric current and its effects

Laws of heating is given by :

  1. Joule

  2. Ohm

  3. Maxwell

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

Answer is A.

The heat which is produced due to the flow of  current   within an electric wire, is expressed in Joules.
James Prescott Joule was an English physicist who studied the nature of heat and established its relationship to mechanical work. He therefore laid the foundation for the theory of conservation of energy, which later influenced the First Law of Thermodynamics. He also formulated the Joules laws which deal with the transfer of energy.

Multiple choice physics electrical circuits domestic electric circuits and safety precautions domestic and commercial circuit electric power

Mircrowave oven acts on the principle of 

  1. Giving rotational energy to water

  2. Giving translational energy to water molecular

  3. Giving vibrational energy to water molecules

  4. None of these
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Microwave oven act on the principle of transferring electron from lower 

to higher energy level in water molecule.

Multiple choice chemistry non-metals introduction to non-metals occurence of metals occurrence of metals and non metals

Heat conduction is the property of __________.

  1. Non-metals

  2. Metals

  3. Metalloids

  4. All of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Heat conduction is the property of metals. In metals, valance electron is free to flow among the atoms. Because of that metals are such good conductors of electricity. These electrons can also carry energy in the form of heat and thus the metals are conductors of heat.


Hence, the correct option is $B$

Multiple choice movement in plants living world of plants - plant physiology biology

Thermonastic movement is related to

  1. Light

  2. Touch

  3. Chemical

  4. High temperature
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Nastic movement is non-directional movement shown by plant part in response to external stimuli. Thermonastic movement is response shown by plant part to high temperature. Photonastic movement is the response to light. Thigmonastic movement is the response to touch. Chemonastic movement is the response to the chemical.

Thus, the correct answer is option D.

Multiple choice evs the unique world of insects and animals sleeping time animal senses sense organs in animals sense organs in humans

The following detects infrared energy (heat)

  1. chemoreceptors

  2. photoreceptors

  3. mechanoreceptors

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

(A)Chemoreceptor - Receptor that responds to chemicals.

(B)Photoreceptor - Receptor that responds to light.
(C)Mechanoreceptor - Receptor that responds to pressure, position, acceleration.
(D)Thermoreceptor -Receptor that responds to heat.
So, the correct option is 'Thermoreceptor'.

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

Name a medium which is a good insulator of heat.

  1. Still (or trapped) air

  2. Oil

  3. Steam

  4. solid copper
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Trapped(still) air is good insulator.
Thermal conductivity of air is small as compared to solid and liquid. Eg- glass conducts 30 times more power per unit distance per unit temperature than air.
The less dense the material, the less thermal conductivity. And gas(air) is least dense than solid and liquid.
Multiple choice physics heat energy transfers heat and heat transfer heat energy transfer transfer of heat

A cotton sheet is ironed with hot electricity. How is energy transferred through the metal base of the iron to the sheet?

  1. by conduction only

  2. by convection only

  3. by radiation only

  4. by convection and radiation only
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Conduction occurs when two objects at different temperatures are in contact with each other. Heat flows from the warmer to the cooler object until they are both at the same temperature.
The iron and cotton sheet is in contact with each other so, there is conduction between them.

Energy transformation while ironing clothes takes out their wrinkles and makes them smooth. This takes the heat, which is one type of energy. In the iron, electrical energy is used, and it is transformed into heat energy.