mikhailpavel said:
Our professor said that when a metallic body or a conductor is inserted inside a gaussian sphere, it will not experience anykind of electric force? But i don't understand why? Any help will be appreciable.
I'm not sure if i fully understand your question but maybe this input can provide some clarity.(i just passed E/M last semester with an A so keep that in mind with what I'm going to be saying and people that post after me, please be kind to a newbie (me) as I am no where near all knowing in physics, just a step ahead of the OP)
I am guessing your professor is introducing the Faraday Cage phenomenon (if that is the right word for it) that there will be no electric field within a conducting sphere with a static charge because static charge in a conductor is distributed along the surface of the conductor.
Now again, take what i say with a grain of salt as I am just trying to help get you in the mode of this Gaussian stuff to help you sort out your confusions
Think about the equations and what exactly the individual components of the formulas from Gauss and the force exerted by an electric field on a charge:
The surface integral of (E <dot> dA) = Charge enclosed / epsilon naught
and F=Eq
Now think about a spherical conductor that is hollow inside (a shell) with a charge q distributed evenly. Walk through the steps of constructing a spherical Gaussian surface inside the space within the shell (q enclosed is 0) and around the entirety of the conducting sphere (q enclosed is q)
Again, I think the question you posted isn't exactly what your professor said so its hard to help you sort out your confusion (that and I'm still a novice at this stuff as well :) )
Post up some more info like a problem that has the issues that are confusing you and I (as well as others hopefully) can help you.
Sorry if this is a bit choppy, I'm in class :/ i'll come back this evening when I have my notes in front of me and I can try to help you better
-GL
