AP Physics C Electricity and Magnetism Question of the Day

1. Electric field lines may cross one another in regions where the field is particularly strong.
2. Electric field lines always begin on positive charges and must terminate on negative charges.
3. The tangent to an electric field line at any point gives the direction of the electric field at that point. (correct answer)
4. The spacing between electric field lines is uniform in the field created by a single isolated point charge.

Explanation: By convention, the direction of the electric field vector at any point in space is tangent to the electric field line passing through that point. Field lines cannot cross, as this would imply two different field directions at a single point. Field lines can originate from or terminate at infinity. The spacing indicates field strength, which varies for a point charge.