$($a$)$ How strong is the attractive force between a glass rod with a

C $\mathrm{.}0700$

charge and a silk

cloth with a

$\mathrm{.}0600$C

charge, which are $12\mathrm{.}0$ cm apart, using the approximation that they

act like point charges? $($b$)$ Discuss how the answer to this problem might be affected if the

charges are distributed over some area and do not act like point charges.