Quiz 2 results

Once again, you all did very well on the quiz. The average was 81%, which I was quite happy with. Gauss' law still causes a bit of trouble (#3), as do forces in general (#4). Remember, Gauss' law tells us that the electric field on a surface depends only on the total charge enclosed by that surface. If an equal amount of positive and negative charge is enclosed, that adds up to zero, and the field is zero on that surface.

I think the tricky point on #4 is that the electron is far lighter than the proton even though they have equal but opposite charges.

Given the same electric field, they have the same force, but in opposite directions. The acceleration resulting from this force - a = F/m - is greater for a lighter charge, however.

Here is the quiz 2 solution for reference. Note that all of these problems came from the notes directly, if you missed any of these questions, you may want to reread that section and the more detailed solutions.