Contour maps like the one above show equally spaced lines of constant elevation at the Earth's surface. Please explain in what sense they are "equally spaced." Also, please explain in what sense these lines could be called gravitaional equipotentials.

Estimate the total charge that passes through a lightbulb in one second.
Hint: You can use "common" values for the voltage and the power.

Is it possible for a point in space to have zero field and positive potential? How about zero potential and possitive field? Is it possible for the potential to be different from point to point in a region where the field is constant?

A fresh "D cell" battery can provide about 5000 J of electrical energy before it must be discarded. Estimate the number of coulombs that must pass through it during it's lifetime.