Which of the following statements is wrong ?

(1) Rough surfaces are better radiators than smooth surface

(2) Highly polished mirror like surfaces are very good radiators

(3) Black surfaces are better absorbers than white ones

(4) Black surfaces are better radiators than white

Half part of ice block is covered with black cloth and rest half is covered with white cloth and then it is kept in sunlight. After some time clothes are removed to see the melted ice. Which of the following statements is correct ?

(1) Ice covered with white cloth will melt more

(2) Ice covered with black cloth will melt more

(3) Equal ice will melt under both clothes

(4) It will depend on the temperature of surroundings of ice

If between wavelength $\mathrm{\lambda }$ and $\mathrm{\lambda }+\mathrm{d\lambda }$, ${\mathrm{e}}_{\mathrm{\lambda }}$ and ${\mathrm{a}}_{\mathrm{\lambda }}$ be the emissive and absorptive powers of a body and ${\mathrm{E}}_{\mathrm{\lambda }}$ be the emissive power of a perfectly black body, then according to Kirchoff's law, which is true ?
(1) ${\mathrm{e}}_{\mathrm{\lambda }}$= ${\mathrm{a}}_{\mathrm{\lambda }}$= ${\mathrm{E}}_{\mathrm{\lambda }}$          

(2) ${\mathrm{e}}_{\mathrm{\lambda }}$${\mathrm{E}}_{\mathrm{\lambda }}$=${\mathrm{a}}_{\mathrm{\lambda }}$

(3) ${\mathrm{e}}_{\mathrm{\lambda }}$= ${\mathrm{a}}_{\mathrm{\lambda }}$${\mathrm{E}}_{\mathrm{\lambda }}$              

(4) ${\mathrm{e}}_{\mathrm{\lambda }}$${\mathrm{a}}_{\mathrm{\lambda }}$${\mathrm{E}}_{\mathrm{\lambda }}$ = constant

When p calories of heat is given to a body, it absorbs q calories; then the absorbtion power of body will be ?
(1) p/q                         

(2) q/p

(3) ${\mathrm{p}}^2/{\mathrm{q}}^2$                     

(4) ${\mathrm{q}}^2/{\mathrm{p}}^2$

There is a rough black spot on a polished metallic plate. It is heated upto 1400 K approximately and then at once taken in a dark room. Which of the following statements is true ?

(1) In comparison with the plate, the spot will shine more

(2) In camparison with the plate, the spot will appear more black

(3) The spot and the plate will be equally bright

(4) The plate and the black spot can not be seen in the dark room

Which of the following is the example of ideal black body ?

(1) Kajal                                 

(2) Black board

(3) A pin hole in a box             

(4) None of these

Which of the following law states that “good absorbers of heat are good emitters”  ?
(1) Stefan’s law               

(2) Kirchoff’s law

(3) Planck’s law               

(4) Wein’s law

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