If ${\lambda }_m$ is the wavelength, corresponding to which the radiant intensity of a block is at its maximum and its absolute temperature is T, then which of the following graph correctly represents the variation of T?

1.		2.
3.		4.

A black body is at a temperature of 5760 K. The energy of radiation emitted by the body at a wavelength of 250 nm is U₁, at a wavelength of 500 nm is U₂ and that at 1000 nm is U₃. Given Wien's constant $b=2.88\times {10}^6$ $nm-\mathrm{K,\; which }$of the following is correct?
1. U₃=0       
2. U₁>U₂
3. U₂>U₁     
4. U₁=0
 

A piece of iron is heated in a flame. It first becomes dull red then becomes reddish yellow and finally turns to white hot. The correct explanation for the above observation is possible by using

(1) Stefan's law

(2) Wien's displacement law

(3) Kirchoff's law

(4) Newton's law of cooling

According to Wein's law:
1. ${\mathrm{\lambda }}_{\mathrm{m}}\mathrm{T}$= constant                 

2. $\frac{{\mathrm{\lambda }}_{\mathrm{m}}}{\mathrm{T}}$= constant

3. $\frac{T}{{\mathrm{\lambda }}_{\mathrm{m}}}$= constant                 

4. $\mathrm{T}+{\mathrm{\lambda }}_{\mathrm{m}}$= constant

On investigation of light from three different stars A, B and C, it was found that in the spectrum of A the intensity of red colour is maximum, in B the intensity of blue colour is maximum and in C the intensity of yellow colour is maximum. From these observations it can be concluded that

(1) The temperature of A is maximum, B is minimum and C is intermediate

(2) The temperature of A is maximum, C is minimum and B is intermediate

(3) The temperature of B is maximum, A is minimum and C is intermediate

(4) The temperature of C is maximum, B is minimum and A is intermediate

The wavelength of radiation emitted by a body depends upon 

(1) The nature of its surface

(2) The area of its surface

(3) The temperature of its surface

(4) All the above factors

If black wire of platinum is heated, then its colour first appear red, then yellow and finally white. It can be understood on the basis of 

(1) Wien's displacement law

(2) Prevost theroy of heat exchange

(3) Newton's law of cooling

(4) None of the above

Colour of shining bright star is an indication of its

(1) Distance from the earth             

(2) Size

(3) Temperature                             

(4) Mass

A black body at \(200\) K is found to emit maximum energy at a wavelength of \(14\) \(\mu \)m. When its temperature is raised to \(1000\) K, the wavelength at which maximum energy is emitted will be:

If the temperature of the sun becomes twice its present temperature, then: