Intensity ( E ) = d V/ d R

V = potential,  r = distance

E at a point inside a spherical shell is zero.

But  V at that point is minus (-) G M by (/)R

( M- mass ,R- radius of shell )

How ?????????????Pliz explain ...............................

Another way of understanding this is that work is done only from bringing the particle from infinity to the surface of the sphere which gives the potential as -GM/R

Thereafter, no work is done as the field inside is zero. Hence, the potential is the same throughout inside the shell.