A long solenoid has radius a and number of turns per unit length n. If it carries a current I, then the magnetic field on its axis is directly proportional to
Correct answer: B. nl
- A. anl
- B. nl
- C. nI/a
- D. n^2l
Explanation
B is the correct answer. The magnetic field B inside a long solenoid is directly proportional to the number of turns per unit length n and the current I flowing through it. Thus, B∝nI.
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