4.1. The value of E at P (ρ = 2, φ = 40◦ , z = 3) is given as E = 100aρ − 200aφ + 300az V/m.
Determine the incremental work required to move a 20 µC charge a distance of 6 µm:
a) in the direction of aρ : The incremental work is given by dW = −q
3.1. An empty metal paint can is placed on a marble table, the lid is removed, and both parts are
discharged (honorably) by touching them to ground. An insulating nylon thread is glued to
the center of the lid, and a penny, a nickel, and a dime