Two concentric shells of mass `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. `I = (G(M_(1) + M_(2)))/(r^(2))" for "r lt r_(1)`
B. `I = (G(M_(1) + M_(2)))/(r^(2))" for "r lt r_(2)`
C. `I = G( M_(2))/(r^(2))" for "r_(1) lt r lt r_(2)`
D. `I = (G M_(1))/(r^(2))" for "r_(1) lt r lt r_(2)`

Answer

D

Explanation

Gravitational field on a mass m due to oute shell (radius `r_(2)`) behaves like mass placed at the centre so `I = (GM_(1))/(r^(2))` for `r_(1) lt r lt r_(2)`