1. Two point charges q₁ and q₂ are 3.00 m apart, and their total charge is 20 C . (a) If the force of repulsion between them is 0.075N, what are magnitudes of the two charges? (b) If one charge attracts the other with a force of 0.525N, what are the magnitudes of the two charges? Note that you may need to solve a quadratic equation to reach your answer.

2. (a) Find the electric field at the location of q_a in Figure 18.54, given that q_b = +10.00 C and q_c = -5.00 C . (b) What is the force on qa , given that qa = +1.50 nC ?

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