1. | \(\left(\dfrac{\alpha}{\sigma \times 4 \pi R^2}\right)^{\dfrac{1}{4}}\) | 2. | \(\left(\dfrac{\sigma \times 4 \pi R^2}{\alpha}\right)^{\dfrac{1}{4}}\) |
3. | \(\left(\dfrac{\alpha}{\sigma \times 4 \pi R^2}\right)\) | 4. | \(\left(\dfrac{4 \pi R^2 \times \sigma}{\alpha}\right)\) |
1. | \(4\) | increases by a factor of
2. | \(2\) | increases by a factor of
3. | remains unchanged |
4. | decreases by a factor of \(2\) |
The total radiant energy per unit area, normal to the direction of incidence, received at a distance \(R\) from the centre of a star of radius \(r,\) whose outer surface radiates as a black body at a temperature \(T\) K is given by: (Where \(\sigma\) is Stefan’s constant):
1. \(\dfrac{\sigma r^{2}T^{4}}{R^{2}}\)
2. \(\dfrac{\sigma r^{2}T^{4}}{4 \pi R^{2}}\)
3. \(\dfrac{\sigma r^{2}T^{4}}{R^{4}}\)
4. \(\dfrac{4\pi\sigma r^{2}T^{4}}{R^{2}}\)
1. | Both size gulab jamuns will get heated in the same time. |
2. | Smaller gulab jamuns are heated before bigger ones. |
3. | Smaller pizzas are heated before bigger ones. |
4. | Bigger pizzas are heated before smaller ones. |