84. A small ball of mass m = 3.2 g is suspended on a silk thread. The charge q = 16 ∙ 10−9 C is communicated to the ball. At what distance (in mm) from it is it necessary to bring to it from below the same charge of the same name, so that the tension force of the thread is reduced by half?

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