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