MyQuestionIcon

1

You visited us 1 times! Enjoying our articles? Unlock Full Access!

Radiation

If heat is re...

Question

If heat is received by a body from a source only by radiation, how is medium in between them, affected?

Open in App

Solution

Thermal Radiation occurs through a vacuum or any transparent medium (solid or fluid). It is the transfer of energy by means of photons in electromagnetic waves.Thermal radiation is a direct result of the random movements of atoms and molecules in matter. Since these atoms and molecules are composed of charged particles (protons and electrons), their movement results in the emission of electromagnetic radiation, which carries energy away from the surface.So, the medium remains unaffected.

Suggest Corrections

thumbs-up

0

Similar questions

Q. Statement - 1 : Due to the motion of listener, the frequency of the sound waves (as received by listener) emitted by stationary source is affected.
Statement - 2 : Due to the motion of source, wavelength of the sound waves (emitted by source) as received by stationary listener is affected.
Statement - 3 : If receiver and source both are moving, the observed frequency must be different from the original frequency of source.
Treat motion of source or listener as always along a line joining them for all above cases.

Q. In a room containing air, heat can go from one place to another

(a) by conduction only
(b) by convection only
(c) by radiation only
(d) by all the three modes

Q. Which part of the human body is first adversely affected by nuclear radiation?

Q. Statement 1: All hot bodies radiate heat.
Statement 2: Medium is required for transfer of heat by the process of radiation.

Q. All bodies emit heat energy from their surfaces by virtue of their temperature. This heat energy is called radiant energy of thermal radiation. The heat that we receive from the sun is transferred to us by a process which, unlike conduction or convection, does not require the help of a medium in the intervening space which is almost free of particles. Radiant energy travels in space as electromagnetic spectrum. Thermal radiations travel through vacuum with the speed of light. Thermal radiations obey the same laws of reflection and refraction as light does. They exhibit the phenomena of interference, diffraction and polarization as light does.
The emission of radiation from a hot body is expressed in terms of that emitted from a reference body (called the black body) at the same temperature. A black body absorbs and hence emits radiations of all wavelengths. The total energy E emitted by a unit area of a black body per second is given by

E = σ T^{4}

where T is the absolute temperature of the body and

σ

is a constant known as Stefan's constant. If the body is not a perfect black body, then

E = ε σ T^{4}

ε

is the emissivity of the body.
The rate at which energy is radiated by a body depends upon :

View More

Join BYJU'S Learning Program

similar_icon

Related Videos

lock

Algebraic Identities

PHYSICS

Watch in App

explore_more_icon

Explore more

Standard VII Physics

Join BYJU'S Learning Program

CrossIcon