Three metal rods of the same material an identical in all respects are joined as shown in the figure. The temperatures at the ends are maintained as indicated. Assuming no loss of heat from the curved surfaces of the rods, the temperature at the junction $X$ would be ....... $^oC$

A black body at $1227\,^oC$  emits radiations with maximum intensity at a wavelength of $5000\,\mathop A\limits^o $ . If the temperature of the body is increased by $1000\,^oC,$  the maximum intensity will be at ....... $\mathop A\limits^o $

Six identical rods are arranged as shown in the figure. The temperature of the junction $B$ will be......... $^oC$

Gravitation force is required for

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 ........ $\overset{o}{\mathop{A}}$

Two large holes are cut in a metal sheet. If this is heated, distances $AB$ and $BC$, (as shown)