2.1 consider an ideal gas of degenerate, non-relativistic electrons with a concentration n and obtain an expression for the fermi energy. assume now that the gas has a temperature t such that the quantum concentration nq, given by eq. (2.22), is equal to the actual concentration; n quantum effects will be important in such a gas, but the electrons will not be completely degenerate. find the ratio of kt to the fermi energy.

as we know our atmosphere or air have different levels. every level has other gasses, and every gas has another permeability. when the light comes from lower permeability to higher permeability, it changes its direction. so that means that when the light comes from the moon to the earth, it changes it's direction many more times. it basically means that the shape of the light part of the moon is changed on the earth.

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