A charge of 12 µC is uniformly distributed on the surface of a rectangular metallic plate 4 m x 1.5 m, placed in air. Determine the outward pull on the plate.

a) A charge 4Q is located at x = −2l on the x-axis, and a charge Q is located at x = l on the x-axis. Q > 0. Near the origin, a positive test charge q with mass m undergoes small oscillations along the x-axis. What is the frequency ω of these oscillations? (Remember that if F = ma = −kx, then ω2 = k/m).

A charged 3.60 g glass bead hangs suspended in the air by an electric field. If the bead was charged by the removal of 7.10×1010 electrons, what must the electric field magnitude be?  2.56×1011 N/C 3.11×106 N/C 4.97×10-13 N/C 3.17×108 N/C

Two very small spherical  metal objects, each with 1 coulomb of charge, are brought together in a vacuum so that the separation distance between their centers is 1 mm.  what is the force of repulsion between the two objects? (Coulombs constant is k= 9.0 x 10^9) . Answer is 9 x 10^15 N . Would like to see how that answer is gotten.