1. Define potential difference. What is the difference between electric potential and electric potential energy? What is the unit for potential difference?
2. What two units are used for electric fields? Write out the units of both to show that they are equivalent.
3. Why are the electric field lines always perpendicular to equipotential lines?
4. Why can electric field lines never cross?
5. The LED will only light up if enough electrical current is flowing through it. The amount of current is given by I = V/R, where V is the potential difference. Why does it only light up when it is pointing in the same direction as the electric field?