Two point charges, ?10 nC and +18 nC , are held fixed a distance 0.50 m apart. Assume that both charges lie on x-axis, for the -10 nC x = 0 and for the +18 nC charge x = 0.50 m .
Express your answer to two significant figures and include the appropriate units.
A) Where can a +20 nC charge be placed so that the net force on it is zero?
B) Repeat part A if the third charge is ?20 nC.