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Stefan-Boltzman's Law

Consider the ...

Question

Consider the following statements.
$1.$ Thermal radiation are electromagnetic waves.
$2.$ Thermal radiations are reflected from mirror.
$3.$ All bodies emit thermal radiations at all temperature.
$4.$ Thermal radiations of all wavelengths travel in free space with same velocity.
Which of the statement(s) given above are correct?

A

1, 2

and

3

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B

1, 3

and

4

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C

1, 2

and

4

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D

1, 2, 3,

and

4

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Solution

The correct option is D $1, 2, 3,$ and $4$
Thermal radiations are Electromagnetic in nature and fall into infrared range of frequencies. These are radiated by all bodies having a non-zero absolute temperature. As these are Electromagnetic, thermal radiations can reflect and refract, and travel with speed of light in free space. So, all statements are correct.

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Similar questions

Q. Consider the following statements.

1.

Stefan's constant is the same for all black bodies.

2.

Thermal radiations travel with the speed of

3 \times 10^{8} m / s

.

3.

Thermal radiation exhibit diffraction.

4.

Stefan's law is applicable for all heated bodies.
Which of the statements given above are correct?

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 polarisation 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}

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.
In which region of the electromagnetic spectrum do thermal radiations lie?

Q. Assertion (A): Thermal radiations are electromagnetic radiation with wave lengths greater than visible light.
Reason (R): Thermal radiations can propagate through vacuum.

Q. Assertion : Like light radiation, thermal radiations are also electromagnetic radiation.
Reason : Thermal radiation require no medium for propagation.

Q. Thermal radiations are electromagnetic waves belonging to

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