A 5kg book rests on a table. How much force is it exerting on the table?
2 answers:
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Answer:
efficiency of solar panel is 18%
Explanation:
Energy received by the sunlight is given as
here we know the dimensions of the plate as
now we have
now the power received by the sun light is given as
now the output power due to solar panel is given as
now the efficiency is given as
Answer:
The farther star will appear 4 times fainter than the star that is near to the observer.
Explanation:
Since it is given that the luminosity of the 2 stars is same thus they radiate the same energy per unit time
Consider a spherical wave front of energy 'E' that leaves both the stars (Both radiate 'E' as they have same luminosity)
This Energy is spread over the whole surface area of sphere Thus when the wave front is at a distance 'r' the energy per unit surface area is given by
For the star that is twice away from the earth the distance is '2r' thus we will receive an energy given by
Hence we sense it as 4 times fainter than the nearer star.