14.
(a) The area of a sphere may be written 4πR
2
= πD
. Thus,
σ =
q
πD
=
2.4
× 10
−6
C
π(1.3 m)
= 4.5
−7
C/m
.
(b) Eq. 24-11 gives
E =
σ
ε
o
4.5
8.85
−12
/N
·m
= 5.1
4
N/C .