Help part b .http://oi41.tinypic.com/30rv505.jpg
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A positive charge should be placed so that the it will oppose the field at point A
kq3/r^2 = 0.3
r = 3 m
9e9*q3 / 9 = 0.3
q3 = 3.e-10 C = 0.3 n C
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kq3/r^2 = 0.3
r = 3 m
9e9*q3 / 9 = 0.3
q3 = 3.e-10 C = 0.3 n C
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