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Dark lines in the solar spectrum are known as

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Important Questions on Bohr Model, X-ray Spectra, Wave-Particle Duality

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Physics>Modern Physics>Bohr Model, X-ray Spectra, Wave-Particle Duality>Absorption Spectra and Fraunhofer Lines
In the case of black body for energy distribution, energy radiated by a blackbody which is given by, Planck's formula reduces to Rayleigh Jean's formula for
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Physics>Modern Physics>Bohr Model, X-ray Spectra, Wave-Particle Duality>Absorption Spectra and Fraunhofer Lines
Blue colour of the sky is due to
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Physics>Modern Physics>Bohr Model, X-ray Spectra, Wave-Particle Duality>Absorption Spectra and Fraunhofer Lines
The ideal black body is :
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Physics>Modern Physics>Bohr Model, X-ray Spectra, Wave-Particle Duality>Absorption Spectra and Fraunhofer Lines
An ideal black body at room temperature is thrown into a furnace. It is observed that
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Physics>Modern Physics>Bohr Model, X-ray Spectra, Wave-Particle Duality>Absorption Spectra and Fraunhofer Lines
The solar spectrum is an example of
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Physics>Modern Physics>Bohr Model, X-ray Spectra, Wave-Particle Duality>Absorption Spectra and Fraunhofer Lines
The absorptive power of a perfectly black body is 
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Physics>Modern Physics>Bohr Model, X-ray Spectra, Wave-Particle Duality>Absorption Spectra and Fraunhofer Lines
The surface of a black body is at a temperature 727 oC and its cross section is 1 m2 . Heat radiated from this surface in one minute in joules is (Stefan's constant 5.7×10-8 W m-2 K-4 )
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Physics>Modern Physics>Bohr Model, X-ray Spectra, Wave-Particle Duality>Absorption Spectra and Fraunhofer Lines
Four indentical calorimeters painted in different colours, are heated to same temperature and then allowed to cool in vacuum. Which will cool fastest ?
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Physics>Modern Physics>Bohr Model, X-ray Spectra, Wave-Particle Duality>Absorption Spectra and Fraunhofer Lines

A polished metal plate with a rough black spot on it is heated to about 1400 K and quickly taken to a dark room. The spot will appear

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Physics>Modern Physics>Bohr Model, X-ray Spectra, Wave-Particle Duality>Absorption Spectra and Fraunhofer Lines
A good absorber is
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Physics>Modern Physics>Bohr Model, X-ray Spectra, Wave-Particle Duality>Absorption Spectra and Fraunhofer Lines
The temperature at which a black body ceases to radiate energy, is
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Physics>Modern Physics>Bohr Model, X-ray Spectra, Wave-Particle Duality>Absorption Spectra and Fraunhofer Lines
Two thermometers A and B are exposed to sunlight. The valve of A is painted black, but that of B is not painted. The correct statement regarding this case is 
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Physics>Modern Physics>Bohr Model, X-ray Spectra, Wave-Particle Duality>Absorption Spectra and Fraunhofer Lines
If a carved black utensil is heated to high temperature and then brought in dark then :
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Physics>Modern Physics>Bohr Model, X-ray Spectra, Wave-Particle Duality>Absorption Spectra and Fraunhofer Lines
An ideal black body, at room temperature, is thrown into a furnance. It is observed that,
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Physics>Modern Physics>Bohr Model, X-ray Spectra, Wave-Particle Duality>Absorption Spectra and Fraunhofer Lines
A spherical body of area A, and emissivity e=0.6 is kept inside a black body. What is the rate at which energy is radiated per second at temperature T.
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Physics>Modern Physics>Bohr Model, X-ray Spectra, Wave-Particle Duality>Absorption Spectra and Fraunhofer Lines
An ideal black body at room temperature is thrown in a furnance. It is observed that
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Physics>Modern Physics>Bohr Model, X-ray Spectra, Wave-Particle Duality>Absorption Spectra and Fraunhofer Lines
A spherical black body with a radius of 12 cm radiates 450 Watt power at 500 K. If the radius were halved and the temperature doubled, the power radiated in Watt would be ?
 
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Physics>Modern Physics>Bohr Model, X-ray Spectra, Wave-Particle Duality>Absorption Spectra and Fraunhofer Lines
A neon sign does not produce
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Physics>Modern Physics>Bohr Model, X-ray Spectra, Wave-Particle Duality>Absorption Spectra and Fraunhofer Lines
At the time of total solar eclipse, the spectrum of solar radiation will have
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Physics>Modern Physics>Bohr Model, X-ray Spectra, Wave-Particle Duality>Absorption Spectra and Fraunhofer Lines
When the temperature of a black body increases, it is observed that the wavelength corresponding to maximum energy changes from 0.26 μm to 0.13 μm. The ratio of emissive powers of the body at the respective temperature is