0
$\begingroup$

Given this picture, I've understood that giver r>R, E = q/(4πεR^2) but I just can't get why inside the sphere, E equals 0? And the notes don't explain something. I've tried to look it up on the web and found similar examples that don't explain it either...

enter image description here

$\endgroup$
7
  • $\begingroup$ For the exact same reason there is no gravity inside the Earth. $\endgroup$
    – Ryan Unger
    Feb 3, 2015 at 10:44
  • 1
    $\begingroup$ possible duplicate of Inside a conductor? $\endgroup$ Feb 3, 2015 at 10:51
  • 1
    $\begingroup$ 0celo7: the only place inside the Earth where the gravity is zero is at the centre. By contrast the field is zero everywhere inside a conductor. $\endgroup$ Feb 3, 2015 at 10:53
  • $\begingroup$ @JohnRennie: I should have said hollow sphere, correct? My bad. $\endgroup$
    – Ryan Unger
    Feb 3, 2015 at 12:00
  • $\begingroup$ @0celo7: well yes, there is no gravity inside a hollow shell, but the OP is asking about a solid conductor not a hollow one (or at least they don't specifically say it's hollow). $\endgroup$ Feb 3, 2015 at 12:02

1 Answer 1

0
$\begingroup$

First, the context is electrostatics so we assume the net force on any charged particle is zero; if the net force is not zero, the charged particle will accelerate and the situation would not be static.

Inside a conductor, by definition, charge is free to move; if there is an electric field inside, charge will be accelerated.

Thus, we must conclude that, in the electrostatic case, there is no electric field inside a conductor.

Put another way, if there is an electric field inside, it is not the electrostatic case.

$\endgroup$

Not the answer you're looking for? Browse other questions tagged or ask your own question.