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

- A
$\frac{240}{3}$

- B
$240$

- C
$140$

- D
$\frac{140}{3}$

The radiant energy from sun incident normally at the surface of earth is $20\, kcal/m^2-min$. What would have been the radiant energy incident normally on the earth if the sun had a temperature twice of the present one ......... $kcal/m^2-min$

The spectrum of a black body at two temperature $27\,^oC$ and $327\,^oC$ is shown in the figure. Let $A_1$ and $A_2$ be the areas under the two curves respectively. The value of $\frac {A_2}{A_1}$ is

A rod of length $2m$ at $0^o C$ and having expansion coefficient $ \alpha = (3x + 2) \times 10^{-6}$ $ ^o C^{-1}$ where $x$ is the distance (in $cm$) from one end of rod. The length of rod at $20^o C$ is ......... $m$

Which of the following material is most suitable for cooking utensil?

If the wavelengths of maximum intensity of radiations emitted by the sun and the moon are $0.5\times10^{-6}\, m$ and $10^{-4}\,m$ respectively. The ratio of their temperatures is