Gauss Law

[tandoorichicken]

A point charge Q is at the center of a conducting spherical shell of radius R. The total charge of the shell is -Q. (a) What is the field in the region between the point charge and the shell? (b)What is the field outside the shell?

I think I got part (a): F = \frac{kq_1 q_2}{r^2} = \frac{kQ(-Q)}{R^2} = -\frac{kQ^2}{R^2}
E = \frac{F}{Q} = -\frac{kQ}{R^2}

Not quite sure how to do part (b) though.

[cookiemonster]

Try it using Gauss's Law.

\int_S \boldsymbol{E}\cdot d\boldsymbol{A} = \frac{Q}{\epsilon_0}

What's the total charge enclosed by a surface surrounding both the shell and the point charge?

On a similar account, I suggest having another look at part (a). Try it with Gauss's Law! Gauss makes life easy, not hard.

cookiemonster