Mechanical Engineering

According to Stefan-Boltzmann law, the total radiation from a black body per second per unit area is directly proportional to the

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Question: According to Stefan-Boltzmann law, the total radiation from a black body per second per unit area is directly proportional to the
[A].

absolute temperature

[B].

square of the absolute temperature

[C].

cube of the absolute temperature

[D].

fourth power of the absolute temperature

Answer: Option D

Explanation:

No answer description available for this question.

According to Stefan’s law, the total radiation from a black body per second per unit area is directly proportional to the fourth power of the absolute temperature.

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Question: According to Stefan’s law, the total radiation from a black body per second per unit area is directly proportional to the fourth power of the absolute temperature.
[A].

Correct

[B].

Incorrect

Answer: Option A

Explanation:

No answer description available for this question.

Kirchhoff’s law states that

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Question: Kirchhoff’s law states that
[A].

the total radiation from a black body per second per unit area is directly proportional to the fourth power of the absolute temperature

[B].

the wave length corresponding to the maximum energy is proportional to the absolute temperature

[C].

the ratio of the emissive power and absorptive power of all bodies is the same and is equal to the emissive power of a perfectly black body

[D].

none of the above

Answer: Option C

Explanation:

No answer description available for this question.

According to Prevost’s theory of exchanges, every body irrespective of its temperature continuously emit heat radiations to the surrounding bodies and at the same time receives heat radiations from the surrounding bodies.

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Question: According to Prevost’s theory of exchanges, every body irrespective of its temperature continuously emit heat radiations to the surrounding bodies and at the same time receives heat radiations from the surrounding bodies.
[A].

True

[B].

False

Answer: Option A

Explanation:

No answer description available for this question.

An infinite parallel planes with emissivities e1 and e2, the interchange factor for radiation from surface 1 to surface 2 is given by

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Question: An infinite parallel planes with emissivities e1 and e2, the interchange factor for radiation from surface 1 to surface 2 is given by
[A].

[B].

[C].

e1 + e2

[D].

e1e2

Answer: Option A

Explanation:

No answer description available for this question.

If the energy radiated per second per sq. cm. of the surface for wave lengths lying between λ, and λ + dλ is represented by (eλ.dλ), then eλ is called

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Question: If the energy radiated per second per sq. cm. of the surface for wave lengths lying between λ, and λ + dλ is represented by (eλ.dλ), then eλ is called
[A].

absorptive power

[B].

emissive power

[C].

emissivity

[D].

none of these

Answer: Option B

Explanation:

No answer description available for this question.