If wavelengths of maximum intensity of radiations emitted by the sun and the moon are $0.5 \times {10^{ - 6}}m$ and ${10^{ - 4}}m$ respectively, the ratio of their temperatures is
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The energy distribution $E$ with the wavelength $(\lambda )$ for the black body radiation at temperature $T\;Kelvin$is shown in the figure. As the temperature is increased the maxima will
The energy spectrum of a black body exhibits a maximum around a wavelength ${\lambda _o}.$ The temperature of the black body is now changed such that the energy is maximum around a wavelength $\frac{{3{\lambda _o}}}{4}$.The power radiated by the black body will now increase by a factor of
Two identical square rods of metal are welded end to end as shown in figure $(i)$ , $20$ calories of heat flows through it in $4$ minutes. If the rods are welded as shown in figure $(ii)$, the same amount of heat will flow through the rods in ....... $\min.$
Two spheres of the same material have radii $1\; m$ and $4\; m$ and temperatures $4000 \;K$ and $2000 \;K$ respectively. The ratio of the energy radiated per second by the first sphere to that by the second is
The coefficients of thermal conductivity of copper, mercury and glass are respectively $Kc, Km$ and $Kg$ such that $Kc > Km > Kg$ . If the same quantity of heat is to flow per second per unit area of each and corresponding temperature gradients are $Xc, Xm$ and $Xg$ , then
Four rods of same material and having the same cross section and length have been joined, as shown. The temperature of junction of four rods will be........ $^oC$
According to the experiment of Ingen Hausz the relation between the thermal conductivity of a metal rod is $ K$ and the length of the rod whenever the wax melts is