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Question (31)

QN0035772

A black body is at a temperature of . The energy of radiation emitted by this object with wavelength between and is , between and is and between and is . Wien's constant . Then

(A)
(B)
(C)
(D)

Correct Answer: D

Explanation:

From Wien's law, constant, where is the temperature of black body and is the wavelength corresponding to maximum energy of emission. Energy distribution of black body radiation is given below:
(i) and are not zero because a black body emits radiations of nearly all wavelengths.

(ii) Since corresponding to lower wavelength, corresponds to higher wavelength and corresponds to medium wave length, hence .

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Question (32)

QN0035773

A metal ball of surface area 200 square , temperature is surrounded by a vessel at . If the emissivity of the metal is 0.4 , then the rate of loss of heat from the ball is approximately

(A)
108 joule
(B)
182 joule
(C)
168 joule
(D)
192 joule

Correct Answer: C

Explanation:

According to Stefan's Law, the rate of loss of heat is

here sec. ,

So,

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Question (33)

QN0035774

The rectangular surface of area of a black body at temperature emits energy per second. If the length and breadth are reduced to half of the initial value and the temperature is raised to , the rate of emission of energy becomes

(A)
(B)
(C)
(D)

Correct Answer: D

Explanation:

area increases by a factor .

Area increases by a factor .

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Question (34)

QN0035775

Assuming the sun to have a spherical outer surface of radius , radiating like a black body at temperature , the power received by a unit surface, (normal to the incident rays) at a distance
from the centre of the sun is

(A)
(B)
(C)
(D)

Correct Answer: C

Explanation:

Power radiated by the sun at

Power received by a unit surface

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Question (31)

A black body is at a temperature of . The energy of radiation emitted by this object with wavelength between and is , between and is and between and is . Wien's constant . Then

Explanation:

Link:

Question (32)

A metal ball of surface area 200 square , temperature is surrounded by a vessel at . If the emissivity of the metal is 0.4 , then the rate of loss of heat from the ball is approximately

Explanation:

Link:

Question (33)

The rectangular surface of area of a black body at temperature emits energy per second. If the length and breadth are reduced to half of the initial value and the temperature is raised to , the rate of emission of energy becomes

Explanation:

Link:

Question (34)

Assuming the sun to have a spherical outer surface of radius , radiating like a black body at temperature , the power received by a unit surface, (normal to the incident rays) at a distance
from the centre of the sun is

Explanation:

Link:

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Question (31)

A black body is at a temperature of . The energy of radiation emitted by this object with wavelength between and is , between and is and between and is . Wien's constant . Then

Explanation:

Link:

Question (32)

A metal ball of surface area 200 square , temperature is surrounded by a vessel at . If the emissivity of the metal is 0.4 , then the rate of loss of heat from the ball is approximately

Explanation:

Link:

Question (33)

The rectangular surface of area of a black body at temperature emits energy per second. If the length and breadth are reduced to half of the initial value and the temperature is raised to , the rate of emission of energy becomes

Explanation:

Link:

Question (34)

Assuming the sun to have a spherical outer surface of radius , radiating like a black body at temperature , the power received by a unit surface, (normal to the incident rays) at a distance from the centre of the sun is

Explanation:

Link:

Excel With Tutors

ExcelWithTutors

For Student

For Tutors

Learn

OUR POLICY

Assuming the sun to have a spherical outer surface of radius , radiating like a black body at temperature , the power received by a unit surface, (normal to the incident rays) at a distance
from the centre of the sun is