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Which one of ...

Question

Which one of the following statements is not true regarding thermal radiations?

A

All bodies emit thermal radiation at all temperatures

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B

They are electromagnetic in nature

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C

They travel in straight line with a velocity of

3 \times 10^{8}

m/s in free space

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D

They cannot be reflected by mirrors

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Solution

The correct option is D They cannot be reflected by mirrors
All bodies emit thermal radiation at all temperatures.They are electromagnetic in nature and have same speed. But they cannot be reflected by mirror as thermal energy is not visible.

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Similar questions

Q. 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?

Q. Which of the following statements are true regarding heat?
(a) Heat is a form of energy
(b) Heat can be reflected by a mirror
(c) Heat is an electromagnetic radiation
(d) Heat cannot pass through vacuum

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

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E = σ T^{4}

T

is the absolute temperature of the body and

σ

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E = ε σ T^{4}

ε

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

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1.Heat is a form of energy
2.Heat can be reflected by a mirror
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