69. Two point charges, while in air at a distance of 5 cm from each other, interact with each other with a force of F1 = 120 μN, and while in a non-conductive liquid at a distance of 10 cm from each other, interact with a force of F2 = 15 μN. Determine the dielectric tightness of a liquid.

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