Question

A solid conducting sphere of radius $2.00cm$ has a charge of $8.00\mu C$. A conducting spherical shell of inner radius $4.00cm$ and outer radius $5.00cm$ is concentric with the solid sphere and has a charge of $-4.00\mu C$. Find the electric field at (a) $r=1.00cm$,(b) $r=3.00cm$, (c) $r=4.50cm$, and (d) $r=7.00cm$ from the center of this charge configuration.

Answer 1

(a) $\overrightarrow{E}=0$
(b) $E=\frac{k_{e}Q}{r^2}=\frac{(8.99\times {10}^{9}N\cdot m^2/C^2)(8.00\times {10}^{-6}C)}{(0.0300m{)}^2}=7.99\times {10}^{7}N/C$
$\overrightarrow{E}=79.9MN/C$ radially outward
(c) $\overrightarrow{E}=0$
(d) $E=\frac{k_{e}Q}{r^2}=\frac{(8.99\times {10}^{9}N\cdot m^2/C^2)(4.00\times {10}^{-6}C)}{(0.0700m{)}^2}=7.34\times {10}^{6}N/C$
$\overrightarrow{E}=7.34MN/C$ radially outward