Variation of g due to depth

Описание: in this video lecture (Physics) Class XI Chapter Gravitation in Hindi .It is Explained, how acceleration due to gravity (g) varies in the depth of Earth and derived equation g in depth(d)=g(on the surface of Earth) (1-d/R) where R is Radius of Earth. The value of "g" also decreases at the height from Earth surface. and also varies with altitude.