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

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 ?

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

Which of the following law states that “good absorbers of heat are good emitters”  ?

According to Wein's law -

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

The wavelength of radiation emitted by a body depends upon 

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 

Colour of shining bright star is an indication of its

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

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

The maximum energy in the thermal radiation from a hot source occurs at a wavelength of $11\times {10}^{-5}$ cm. According to Wein's law, the temperature of the source (on Kelvin scale) will be n times the temperature of another source (on Kelvin scale) for which the wavelength at maximum energy is $5.5\times {10}^{-5}$ cm. The value n is 
(a) 2                     (b) 4
(c) $\frac{1}{2}$                    (d) 1

How is the temperature of stars determined by ?

On increasing the temperature of a substance gradually, which of the following colours will be noticed by you ?

A black body has a maximum wavelength at a temperature of 2000 K. Its corresponding wavelength at temperatures of 3000 K will be: 

If the temperature of the sun (black body) is doubled, the rate of energy received on earth will be increased by a factor of 

A body cools down from 80°C to 60°C in 10 minutes when the temperature of the surroundings is 30°C. The temperature of the body after the next 10 minutes will be:

A black body at a temperature of 1640 K has the wavelength corresponding to maximum emission equal to 1.75 $\mathrm{\mu m}$. Assuming the moon to be a perfectly black body, the temperature of the moon, if the wavelength corresponding to maximum emission is 14.35 $\mathrm{\mu }$m is

A particular star (assuming it as a black body) has a surface temperature of about $5\times {10}^4 \mathrm{K}$. The wavelength in nanometers at which its radiation becomes maximum is -
(b = 0.0029 mK) 

The intensity of radiation emitted by the sun has its maximum value at a wavelength of 510 nm and that emitted by the north star has the maximum value at 350 nm. If these stars behave like black bodies, then the ratio of the surface temperature of the sun and north star is

The amount of radiation emitted by a perfectly black body is proportional to 

The temperature of an object is $400°\mathrm{C}$. The temperature of the surroundings may be assumed to be negligible. What temperature would cause the energy to radiate twice as quickly?
(Given, \(2^{\frac{1}{4}} \approx 1.18\))

A black body at a temperature of 227$°\mathrm{C}$ radiates heat energy at the rate of 5 $\mathrm{cal}/{\mathrm{cm}}^2-\sec$. At a temperature of $727°\mathrm{C}$, the rate of heat radiated per unit area in $\mathrm{cal}/{\mathrm{cm}}^2$ will be 

Energy is being emitted from the surface of a black body at 127$°\mathrm{C}$ temperature at the rate of $1.0\times {10}^6 \mathrm{J}/\sec -{\mathrm{m}}^2$. Temperature of the black body at which the rate of energy emission is $16.0\times {10}^6 \mathrm{J}/\sec -{\mathrm{m}}^2$ will be -

(a) 254$°\mathrm{C}$          (b) 508$°\mathrm{C}$
(c) 527$°\mathrm{C}$          (d) 727$°\mathrm{C}$

If temperature of a black body increases from $7°C$ to $287°\mathrm{C}$ , then the rate of energy radiation increases by

The area of a hole of heat furnace is ${10}^{-4} {\mathrm{m}}^2$. It radiates $1.58\times {10}^5$ calories of heat per hour. If the emissivity of the furnace is 0.80, then its temperature is

Two spheres P and Q, of same colour having radii 8 cm and 2 cm are maintained at temperatures 127$°\mathrm{C}$and 527$°\mathrm{C}$ respectively. The ratio of energy radiated by P and Q is 

A body radiates energy 5W at a temperature of 127$°\mathrm{C}$. If the temperature is increased to 927$°\mathrm{C}$, then it radiates energy at the rate of

The temperatures of two bodies A and B are respectively 727$°\mathrm{C}$ and 327$°\mathrm{C}$. The ratio of the rates of heat radiated by them is 

The radiant energy from the sun incident normally at the surface of earth is $20 \mathrm{kcal}/{\mathrm{m}}^2\min$. What would have been the radiant energy incident normally on the earth, if the sun had a temperature twice of the present one ?
(a) $160 \mathrm{kcal}/{\mathrm{m}}^2\min$                    (b) $40 \mathrm{kcal}/{\mathrm{m}}^2\min$
(c) $320 \mathrm{kcal}/{\mathrm{m}}^2\min$                    (d) $80 \mathrm{kcal}/{\mathrm{m}}^2\min$