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

What exactly causes heat to rise?

  1. density increases as temperature increases

  2. density decreases as temperature increases
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

As temperature increases, particles move faster and spread out, which decreases the density of the substance. This decrease in density causes the warmer substance to rise.

Multiple choice

What causes the movement of matter during convection?

  1. hot matter rising

  2. hot matter sinking

  3. cold particles moving into warmer particles

  4. matter does not move during convection
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Convection is driven by the rising of warmer, less dense matter. As it rises, it displaces cooler, denser matter, which then sinks to take its place, creating a convection current.

Multiple choice physics the essence of change different forms of energy energy conversions energy transformations and energy transfers

Iron glows in red colour when it is heated to very high temperature because:

  1. Heat we supply consumes red colour at high temperature

  2. Mechanical energy is being converted into heat energy

  3. Light energy is being converted into heat energy

  4. Heat energy is being converted into light energy
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Iron glows in red colour when it is heated to very high temperature because heat being a form of energy can be transformed into other forms of energy.

Multiple choice physics the essence of change different forms of energy energy conversions energy transformations and energy transfers

The temperature of water at the bottom of a waterfall is higher than that of the water at the top, because:

  1. falling water absorbs heat from the sun.

  2. kinetic energy of the falling water is converted into heat.

  3. water at the bottom has greater potential energy.

  4. the rocks on the river bed give out heat.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

When water is flowing it posses some kinetic energy and also posses some potential energy wrt to the lower level of the waterfall.

When water fall from higher level its potential energy gets converted to kinetic energy and when water reaches to lower level some part of its kinetic energy gets converted to sound energy amd some to heat energy.
So best possible option is option B.

Multiple choice physics the essence of change different forms of energy energy conversions energy transformations and energy transfers

When we rub our hands, which of the following is true?

  1. Mechanical energy converted to heat energy.

  2. kinetic energy converted to heat energy.

  3. Heat energy converted to mechanical energy.

  4. Heat energy converted to kinetic energy.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Rubbing hands involves the movement of muscles (mechanical energy), and the friction generated converts that motion into heat energy.

Multiple choice physics the essence of change different forms of energy energy conversions energy transformations and energy transfers

The temperature of water at the bottom of a large waterfall is generally higher than that of the water at the top, because

  1. the falling water absorbs heat from the sun

  2. the KE of the falling water is converted into heat

  3. the water at the bottom has greater PE

  4. rocks on the bed of the river give out heat
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Water is slightly warmer at the bottom of a waterfall than at the top because the gravitational potential energy is converted first to kinetic energy of the falling water, and finally to heat energy as it comes to rest at the bottom.

Multiple choice physics the essence of change different forms of energy energy conversions energy transformations and energy transfers

The temperature of water at the bottom of a waterfall is higher than that ofthe water at the top, because

  1. falling water absorbs heat from the sun

  2. kinetic energy of the falling water is converted into heat

  3. water at the bottom has greater potential energy

  4. the rocks on the river bed give out heat
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

When water falls from top of a waterfall, it has a force of friction being exerted on it due to which some of its kinetic energy gets converted into heat energy.

Thus the temperature of water at the bottom of waterfall is higher than that at the top.

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

A metal plate can be heated by

  1. passing either a direct or alternating current through the plate.

  2. placing in a time varying magnetic field.

  3. placing in a space varying magnetic field, but does not vary with time.

  4. both (a) and (b) are correct
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

When a metal plate is getting heated, it may be due to the passage of direct current, alternating current or even induced current through the plate. As time varying magnetic field produces induced current  in the plate, so both (a) and (b) are correct.

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

The temperature of a metal wire rises when an electric current is passed through it because:

  1. collision of conduction electrons with the atoms of metal gives them energy which appears as heat

  2. .when electrons fall from higher energy level to lower energy level, heat energy is released

  3. collisions of metal atoms with each other releases heat energy.

  4. collisions of conduction electrons with each other releases heat energy.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Answer is A.

A metallic conductor has a large number of free electrons in it. When a potential difference is applied across the ends of a metallic wire, the free electrons begin to drift from the low potential to the high potential region. These electrons collide with the positive ions (the atoms which have lost their electrons). In these collisions, energy of the electrons is transferred to the positive ions and they begin to vibrate more violently. As a result, heat is produced. Greater the number of electrons flowing per second, greater will be the rate of collisions and hence more heat is produced.
Hence, the temperature of a metal wire rises when an electric current is passed through it because collision of conduction electrons with the atoms of metal gives them energy which appears as heat.

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. increases

  2. decreases

  3. remains same

  4. may increase or decrease
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

As we know,

$Power=I^2R$
Therefore, this power is released in the form of heat in the conductor and this heat increases the temperature of the conductor.
Hence, temperature increases.