30. A small ball with a mass of 1 μg and a charge of 1 nC is attached to a uniformly charged vertical plane. The filament forms an angle of 30 ° with the plane, and the tension force of the filament is 0.1 μN. 1) Find the surface charge density of the plane. 2) How will the angle change if the system is immersed in kerosene (ε = 2)?

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