Goal: Link flux to field lines.
Source: 283-415 nonzero flux?
The circles in the picture below are Gaussian surfaces. All other lines
are electric field lines. For which cases is the flux non-zero?
- a
- a, b, and f
- a, b, e, and f
- a, b, d, e, and h
- a and b
- All but g
- All of them
- None of the above
- Cannot be determined
Commentary:
Answer
(2) As “follow-up” it is good to ask questions about comparisons
between two or more of the situations. For example, which is flux is
larger, a or f? Such questions help determine what students are focused
upon; are they keying on number of lines, do they understand that the
flux can be negative.