The graph shown in the adjacent diagram, represents the variation of temperature (T) of two bodies X and Y having the same surface area, with time (t) due to the emission of radiation. Find the correct relation between the emissivity and absorptivity power of the two bodies ?

      

Variation of radiant energy emitted by sun, filament of tungsten lamp and welding arc as a function of its wavelength is shown in figure. Which of the following options is the correct match ?

       

The earth receives at its surface radiation from the sun at the rate of  1,400 Wm^-2. The distance of the centre of the sun from the surface of the earthy is 1.5 x 10¹¹ m and the radius of the sun is 70 x 10⁸ m. Treating sun as a black body, it follows from the above data that its surface temperature is:

A black body radiates heat energy at the rate of 2 × 10⁵ J/s/m² at a temperature of 127°C. The temperature of black body at which the rate of radiation is 32 × 10⁵ J/s/m² is

The earth radiates in the infra-red region of the spectrum. The spectrum is correctly given by :

Heat current is maximum in which of the following (rods are of identical dimension) ?

A block of ice at - 10^oC is slowly heated and converted to steam at 100^oC. Which of the following curves represents the phenomenon qualitatively ?

Two identical rods are connected between two containers. One of them is at 100^oC and another is at 0^oC. If rods are connected in parallel then the rate of melting of ice is q₁ g/sec. If they are connected in series then the rate is q₂. The ratio q₂/q₁ is:

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 the North Star is:

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