Which one of the following plots represents the variation of gravitational field on a particle with distance r due to a thin spherical shell of radius R? (r is measured from the centre of the spherical shell)
- [figure]
- [figure]
- [figure]
- [figure]
Answer
(2) [figure]
Solution
Inside a thin spherical shell (r < R): gravitational field F = 0.
Outside (r R): the shell behaves as a point mass at its centre F = GMr2
So F is zero up to R, jumps to GMR2 at the surface and then falls as 1r2.
Answer: (2)