1. Two point charges of 120 nC and 800 nC are separated by a distance of 40 cm. How much energy must be expended to reduce the separation to 30 cm?
2. Using (1) and vector operations, show that (a) -E = -∇ V , and (b) ∇ × -E = 0.
3. Show that equipotential surfaces for an infinite, uniformly charged line are concentric cylinders.