In rainy season, on a clear night the black seat of a bicycle becomes wet because -

1. It absorbs water vapour

2. Black seat is good absorber of heat

3. Black seat is good radiator of heat energy

4. None of the above

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

A piece of blue glass heated to a high temperature and a piece of red glass at room temperature, are taken inside a dimly lit room. Then  -

1. The blue piece will look blue and red will look as usual

2. Red look brighter red and blue look ordinary blue

3. Blue shines like brighter red compared to the red piece

4.  Both the pieces will look equally red.

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

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