Question

A 3.5-cm radius hemisphere contains a total charge of 6.6 × 10–7

Answer 1

As per Gauss Law

Net flux through enclosed surface is

$\phi = \frac{Q}{\epsilon_0}$

here through this hemisphere total flux will pass through two portions

1). from the curved surface

2). from flat circular base

so now we have

$\phi_{base} + \phi_{surface} = \frac{Q}{\epsilon_0}$

given that

$Q = 6.6 * 10^{-7} C$

$\phi_{surface} = 9.8 * 10^4$

now we have

$\phi_{base} + 9.8*10^4 = \frac{6.6*10^7}{8.85 * 10^{-12}}$

$\phi_{base} = - 9.8 *10^4 + 7.46 * 10^4$

$\phi_{base} = - 2.34 * 10^4 N*m^2/C$