6. For concreteness, consider that charge 2 lies 0.15 m east of charge 1, and the point at which we are
asked to evaluate their net field is r=0.075 m east of charge 1 and r=0.075 m west of charge 2. The
values of charge are q1=−q2=2.0×10−7C. The magnitudes and directions of the individual fields are
specified:
E1
=q1
4πε0r2=3.2×105N/Cand
E1points east
E2
=|q2|
4πε0r2=3.2×105N/Cand
E2points east
Since they point the same direction, the magnitude of the net field is the sum of their amplitudes,
Enet
=6.4×105N/C, and it points east (that is, towards the negative charge).
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