# Gravitation and gauss' law

1. Aug 6, 2008

### aniketp

hello,
I was wondering if there is an equivalent gauss' law for gravitation like:
$$\Phi$$=4$$\pi$$G*Menclosed
any help would be appreciated. Thank you.

2. Aug 6, 2008

### Staff: Mentor

Absolutely. See: "[URL [Broken] law for gravity[/URL]

Last edited by a moderator: May 3, 2017
3. Aug 6, 2008

### aniketp

thank you. but do magnetic fields have any such law? intuitively, i am inclined to say no,
because magnetic field lines can cross.....but i would like a rigorous proof

4. Aug 6, 2008

### Staff: Mentor

Yes, there's a Gauss's law for magnetic fields--it's one of Maxwell's Equations. Since there are no magnetic monopoles, it is rather simple: http://en.wikipedia.org/wiki/Gauss%27_law_for_magnetism" [Broken].

Magnetic field lines can cross only where the field is zero.

Last edited by a moderator: May 3, 2017
5. Aug 6, 2008

### Defennder

I'm curious as to why there isn't any magnetic monopoles. The freshman physics textbook I read for my intro physics course says that current theory (I think it was Serway) does predict the existence of magnetic monopoles.

6. Aug 7, 2008

### Phrak

No one seems to have found any magnetic monopoles. By including magnetic charge and magnetic current terms in Maxwell's equations you postulate magnetic charge. It brings some (anti-) symmetry to the equations, but this is inconsistence with the magnetic potential.