Exam-style question
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A magnetic field produced by a long straight wire is best described as:.
- A.Radial
- B.Uniform
- C.Both radial and uniform
- D.Neither radial nor uniform
Model answer
What a good answer should say
- Uniform
Explanation
Why this works
Define both: A radial field has lines radiating from a point; a uniform field has straight, parallel lines. Identify key difference: In a long straight wire, the field lines form concentric circles around the wire, which are not parallel but form a pattern that is locally uniform in direction around any small segment.
Explain when each applies: Radial fields arise from point sources; uniform fields arise from extended, evenly distributed sources. Conclude: The magnetic field around a long straight wire is best described as uniform in the sense that its direction is consistent around the wire, not radial.
Common mistake
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