Two concentric shells of masses `M_(1)` and `M_(2)` are having radii `r_(1)` and `r_(2)`. Which of the following is the correct expression for the gravitational field on a mass `m`?

Options

A. `F=(G(M_(1)+M_(2)))/(r_(2)),"for"ltr_(1)`
B. `E=(G(M_(1)+M_(2)))/(r_(2)),"for"ltr_(2)`
C. `E=(GM_(2))/(r_(2)),"for"r_(1)ltrltr_(2)`
D. `E=(GM_(1))/(r_(2)),"for"r_(1)ltrltr_(2)`

Answer

C

Explanation

field at internal point of the shell is zero but at externam point shell behave as if its whole mass at centre.