9
Solution  (a) Field at P due to charge +10 mC
= 
5
12
2
1
2
10
C
4 (8 854 10
C N
m
)
−
−
−
−
π
×
2
4
2
1
(15
0 25)
10
m
−
×
−
×
=  4 13 × 106  N C–1  along BP
Field at P due to charge –10 mC
–5
12
2
1
2
10
C
4 (8