22.
(a) Eq. 22-1 gives
F =
8.99
× 10
9
N
·m
2
/C
1.00
−16
C
(1.00
−2
m)
= 8.99
−19
N .
(b) If n is the number of excess electrons (of charge
−e each) on each drop then
n =
−
q
e
=
−1.00 × 10
1.60
= 625 .