## Physics for Scientists and Engineers: A Strategic Approach with Modern Physics (3rd Edition)

$Q = 80~nC$
We can use the equation for the electric field strength around a spherical shell to find the charge $Q$: $E = \frac{kQ}{r^2}$ $Q = \frac{r^2~E}{k}$ $Q = \frac{(0.12~m)^2(50,000~N/C)}{9.0\times 10^9~N~m^2/C^2}$ $Q = 80~nC$