81. The electric field created by two point charges Q1 = 2 nC and Q2 = -3 nC. The distance between the charges d = 20 cm. Determine the electric field intensity at a point located at a distance r1 = 15 cm from the first charge and r2 = 10 cm from the second charge. What force will act on the charge if it is placed at this point in two cases: a) a charge equal to 5 nC; b) the charge is equal to -5 nC.

Detailed solution. Decorated in Microsoft Word 2003. (Target decided to use formula editor)