00:01
Hi, in this question the radiation, so in the first part of the question we have the radiation from the sun reaches the earth.
00:08
So radiation is a, so radiation from sun reaches the earth like a bundle of energy, so bundle or beam of energy, so beam of energy.
00:20
So the area of cross section, so area of cross section is pi r square is distributed, distributed to the surface of the earth, earth so that the total energy absorbed, so total energy absorbed hitting the earth, so total energy hitting the earth, so hitting earth is equal to it is e absorbed is equal to pi r square d, where d is the intensity of the solar radiation that is 1370 watt per meter square, so d is the intensity of the radiation.
01:15
Then the energy radiated from the earth, so the energy radiated from earth to space, earth to space, so that the total surface area of the earth is total surface of, so total surface area of the earth is 4 pi r square, so this is the first part.
01:47
So in the second part of the question from stefan boltzmann law we have the total power radiated is equal to a into epsilon sigma t power 4, where a is the area of cross section, sigma is the stefan constant, epsilon is the emissivity and t is the absolute temperature in kelvin.
02:03
Now we have the radiative surface area is 4 pi r square and the observable, observable surface area, so pi r square is the observable surface area, whereas 4 pi r square is the radiative surface area...