The power radiated by a black body is $P$ and it radiates maximum energy around the wavelength $\lambda_0$. If the temperature of the black body is now changed so that it radiates maximum energy around wavelength $\frac{3}{4}\lambda_0$, the power radiated by it will increase by a factor of

The temperature of the two outer surfaces of a composite slab, consisting of two materials having coefficients of thermal conductivity $K$ and $2K$ and thickness $x$ and $4x$, respectively are $T_2$ and $T_1(T_2 > T_1)$. The rate of heat transfer through the slab, in a steady state is $\left( {\frac{{A\left( {{T_2} - {T_1}} \right)K}}{x}} \right)f$, with $f$ equals to

In a composite rod, when two rods of different lengths $l_1$ and $l_2$ and of the same cross-sectional area are joined from end to end then if $K$ is the effective coefficient of thermal conductivity,  the value of $(l_1 + l_2)/K$ is

The surface temperature of the sun which has maximum energy emission at $500\, nm$ is $6000\, K$. The temperature of a star which has maximum energy emission at $400\, nm$ will be ........ $K$

A solid cube and a solid sphere of the same material have equal surface area. Both are at the same temperature $120\ ^oC$ , then

Solar radiation emitted by the sun resembles that emitted by a black body at a temperature of $6000\, K$. Maximum intensity is emitted at a wavelength of about $4800\,\mathop A\limits^o $. If the sun was cooled down from $6000\, K$ to $3000\, K$, then the peak intensity would occur at a wavelength of ......... $\mathop A\limits^o $