69. A plate made from hard rubber thickness d = 2 mm and S = area of 300 cm2 were placed in a uniform electric field intensity E0 = 1 kV / m, is positioned so that its field lines are perpendicular to the flat surface. Find: 1) the density of σ 'related charges on the surface of the wafer; 2) the energy W of the electric field concentrated in the plate.

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