Wien’s Displacement Law

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Wien’s Displacement Law: Overview

This topic covers concepts such as Spectral Energy Distribution Curve, Temperature Effects on Distribution Curve, Wien's Displacement Law, Rayleigh-Jeans Energy Distribution Law, Planck's Explanation on Distribution Curve, and Solar Constant.

Important Questions on Wien’s Displacement Law

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The Wien's displacement law express relation between-

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A black body is at temperature 2880 K. The energy of radiation emitted by the body at wavelength 250 nm is U1, at wavelength 500 nm is U2 and that of 1000 nm is U3. Then the correct answer is (Weins constant b=2.88×106 nmK

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A black body at a temperature of 1227 oC emits radiations of maximum intensity at 5000 Å. Find the wavelength at which the intensity of emitted radiation will be maximum, if the temperature of the body is increased by 1000 oC.

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Solar radiation has maximum intensity at a wavelength of 480 nm in the visible region. Figure out the surface temperature of the sun using this information. (Use Wien's constant b=2.88×10-3 m K)

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If λm denotes the wavelength at which a certain black body radiates maximum intensity for a temperature T K. Then the correct relation will be

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The ratio of temperatures of two stars is 3:2. If the wavelength of maximum intensity of the first star is 4000 A, what is the corresponding wavelength of the second star?

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If the power radiated by three discs A, B and C having radii 2 m, 4 m and 6 m are QA,  QB and QC respectively and are coated with carbon black on their outer surfaces. The wavelength corresponding to their maximum intensities are 300 nm, 400 nm and 500 nm respectively.Then,
 

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A black body emits radiations of maximum intensity at 5000 A when its temperature is 1227°C. If, its temperature is increased by 1000°C  then the maximum intensity of emitted radiation will be at:

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The wavelength of maximum intensity of radiation emitted by a star is 289.8 nm. The radiation intensity of the star is
(Stefan's constant =5.67×10-8 W m-2 K-4, Wien's constant =b=2898 μm K

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Experimental investigation shows that the intensity of solar radiation is maximum for a wavelength 480 nm in the visible region. Estimate the surface temperature of sun. (Given Wien's constant b=2.88×10-3 m K)

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Generally the temperature of a distant star is estimated using

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The earth radiates in the infra-red region of the spectrum. The spectrum is correctly given by

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The black body spectrum of an object Q1 is such that its radiant intensity (i.e., intensity per unit wavelength interval) is maximum at a wavelength of 100 nm. Another object O2 has the maximum radiant intensity at 600 nm. The ratio of power emitted per unit area by source O1 to that of source O2 is

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According to Wien's law

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A black body is at a temperature of 5760 K. The energy of radiation emitted by the body at wavelength 250 nm is U1 , at wavelength 500 nm is U2 and that at 1000 nm is U3 . Wien's constant, b=2.88×106 nmK. Which of the following is correct?

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Following graphs show the variation in the intensity of heat radiations by the black body and frequency at a fixed temperature. Choose the correct option.

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The spectral energy distribution of the Sun (temperature=6050 K) has a maximum at 4753 Å. The temperature of a star for which this maximum is at 9506 Å is

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Following graph shows the correct variation in intensity of heat radiations by black body and frequency at a fixed temperature

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Following graph shows the correct variation in intensity of heat radiations by black body and frequency at a fixed temperature

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On observing light from three different stars P,Q and R, it was found that intensity of violet colour is maximum in the spectrum of P, the intensity of green colour is maximum in the spectrum of R and the intensity of red colour is maximum in the spectrum of Q. If Tp, TQ and TR are the respective absolute temperatures of P, Q and R, then it can be concluded from the above observations that :