# gravitation

multi correct;

in non uniform spherical shell of mass 'm' and radius R (here E is gravitational intensity) which of the following are wrong;

(A) E = 0 (r<R)
(B) âˆ« E.dS = 0 on any closed surface inside the shell
(C) E can not be zero at any point inside the shell
(D) Gravitational potential is zero at any point inside the shell.

• Swaraj Dalmia ·

a)True.Gravitational field inside any hollow mass=0.
b)True.As E=0.
c)false.From a.
d)false.Gravitational Potential will be equal to that on the surface(which is not 0).

Ans:C),D)

• Vivek @ Born this Way ·

I think A,C,D.

• rishabh ·

explaination?

• Vivek @ Born this Way ·

Since, the charge distribution is non uniform , you cannot say for sure that E is zero inside the shell (If it uniform then even you can't. You can just add that E is zero at center), rather you would say the Flux of Electric field is zero.

hence B is True.

Also, there must exist some point(We don't about it) where the E should be zero.

• Vivek @ Born this Way ·

@Risabh What is the correct answer?

• rishabh ·

i gt the same as swaraj.

• Swaraj Dalmia ·

The gravitational field(due to the shell) inside(anywhere) inside a symmetric shell=0.
This is not valid for non-symetric objects.
Taking an example,we can consider almost total mass concentrated at a pt. and the âˆ‚m mass forming rest of shell.Here E=0 everywhere.

This difference(from conductors) is shown because of the fact that mass unlike elec. cant move.This is also responsible for the fact that gravitation shielding doesn't exist.

• Vivek @ Born this Way ·

Oops. I thought that E = Electric field. My answer was presumably for that only.

I would go with C,D then.

• Vivek @ Born this Way ·

On Physics forums, they say A,C,D only.

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