Solar radiation emitted by the sun resembles that emitted by a black body at a temperature of $6000\,K$. Maximum intensity is emitted at wavelength of about $4800{\text{ }}\mathop {\text{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 ........ $\overset{o}{\mathop{A}}$
$4800$
$9600$
$2400$
$19200$
Three copper blocks of masses $M_1, M_2$ and $M_3$ $kg$ respectively are brought into thermal contact till they reach equilibrium. Before contact, they were at $T_1, T_2, T_3(T_1> T_3)$. Assuming there is no heat loss to the surroundings, the equilibrium temprature $T$ is ($s$ is specific heat of copper)
If the temperature of the sun were to increase from $T$ to $2T$ and its radius from $R$ to $2R$, then the ratio of the radiant energy received on earth to what it was previously will be
Two diagonally opposite comers of a square made of a four thin rods of same material, same dimensions are at temperature $40^{\circ} C$ and $10^{\circ} C$. If only heat conduction takes place, then the temperature difference between other two corners will be .......... $^{\circ} C$
Two rods of same length and same area of cross section are joined
Temperature of two ends are as shown in figure. As we move along the rod, temperature are as shown in following
Two rods $A$ and $B$ of same cross-sectional are $A$ and length $l$ connected in series between a source $(T_1 = 100^o C)$ and a sink $(T_2 = 0^o C)$ as shown in figure. The rod is laterally insulated The ratio of the thermal resistance of the rod is