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An electron moving in a circular orbit of radius r makes n rotations per second. The magnetic field produced at the centre has magnitude:
- Zero
- μ₀ne / r
- μ₀ne / 2r
- μ₀ne / 2πr
Correct answer: μ₀ne / 2r
Solution
The magnetic field at the center of a circular loop due to a current is given by B = μ₀I / 2r. Here, the current I is due to the electron's motion, which is I = ne, where n is the frequency of rotation. Substituting I into the formula gives B = μ₀ne / 2r.
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