Goal: Reason about magnetic fields
Source: 283 field of bar magnets
Two
identical bar magnets are placed rigidly and parallel to each other as
shown. At what locations, if any, is the net magnetic field close to
zero?
- A only
- B only
- C only
- D only
- A and B
- A, B, and C
- C and D
- None of the above.
Commentary:
Answer
(3) C is the point of weakest field. The field is weak at A also.
Find out student reasons is more important than the answer. Have
students sketch the field lines. Ask them how is the strength of the
field indicated on a field line diagram.