For a point inside the earth i.e. r<R E=GM∕R3r where M and R be mass and radius of the earth respectively. At the centre, r=0 E=0 For a point outside the earth i.e. $r E=GM∕r2 On the surface of the earth i.e. r=R . E=GM∕R2 The variation of E with distance r from the centre is as shown in the figure.