15)
(ii) For points on the equatorial plane
The magnitudes of the electric fields due to the two
charges +q and –q are given by
E
q
r
a
+q
=
+
4
1
0
2
2
πε
[1 16(a)]
E
q
r
a
–q
=
+
4
1
0
2
2
πε
[1 16(b)]
and are equal The directions of  E+q and E–q are as shown in
Fig