15. At a point in the electric field in the air, a point charge of 3.0 ∙ 10–9 C acts on a force of 1.5 ∙ 10−5 N. Find the field strength at this point and determine the value of the point charge that creates it if this point is removed from a charge of 0.3 m.

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