The graph shows the variation with wavelength of intensity from a unit area of a black body. The scale on the vertical axis on all graphs in this question is the same. The area and the temperatures of the black body are both halved. Which graph now shows the correct variation with wavelength of intensity from a unit area of the body?

The intensity of solar radiations incident on a planet is $\mathrm{S}$ . The diagram represents the energy balance of the planet. The atmosphere reflects an intensity $0.20 \mathrm{S}$and radiates$0.35 \mathrm{S}$. The surface reflects $0.05 \mathrm{S}$ and radiates $0.40 \mathrm{S}$. What is the albedo of the planet.

A nuclear power plant produces $800 \mathrm{MW}$ of electricity with an overall efficiency of$0.32$. The fission reaction taking place in the core of the reactor is:

${}_0{}^1\mathrm{n}+{}_{92}{}^{235}\mathrm{U}\to {}_{54}{}^{140}\mathrm{Xe}+{}_{38}{}^{94}\mathrm{Sr}+2{}_0{}^1\mathrm{n}$ 

 (i) Using the masses provided below show that the energy released in one fission is about $180 \mathrm{MeV}$

${}_0{}^1\mathrm{n}=1.009 \mathrm{u} , {}_{92}{}^{235}\mathrm{U}=235.044 ,{}_{54}{}^{140}\mathrm{Xe}=139.992, {}_{38}{}^{94}\mathrm{Sr}=93.915$

(ii) Estimate the specific energy of $U-235$

(iii)Show that the mass of uranium undergoing fission in one year is about $1500 \mathrm{kg}$

In a nuclear reactor. describe the role of, 

(i) The moderator

(ii) The control rods

(iii) The heat exchanger

In a pumped storage system, the high reservoir of water has area$4.8\times {10}^4{\mathrm{m}}^2$and an average depth of $38 \mathrm{m}$. When the water from the reservoir falls to a lower reservoir, the centre of the mass of the water is lowered by a vertical difference of $225 \mathrm{m}$. The water flows through a turbine connected to a generator at a rate of $350 {\mathrm{m}}^3{\mathrm{s}}^{-1}$.

 Determine the loss of gravitational potential energy when the upper reservoir has been completely emptied.

In a pumped storage system, the high reservoir of water has area$4.8\times {10}^4{\mathrm{m}}^2$and an average depth of $38 \mathrm{m}$. When the water from the reservoir falls to a lower reservoir, the centre of the mass of the water is lowered by a vertical difference of $225 \mathrm{m}$. The water flows through a turbine connected to a generator at a rate of $350 {\mathrm{m}}^3{\mathrm{s}}^{-1}$.

 Estimate the power supply by the falling water.