Moving Charges and Magnetism - Result Question 33

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34. An electron moving in a circular orbit of radius $r$ makes $n$ rotations per second. The magnetic field produced at the centre has magnitude:

======= ####34. An electron moving in a circular orbit of radius $r$ makes $n$ rotations per second. The magnetic field produced at the centre has magnitude:

3e0f7ab6f6a50373c3f2dbda6ca2533482a77bed:content/english/neet-pyq-chapterwise/physics/moving-charges-and-magnetism/moving-charges-and-magnetism—result-question-33.md (a) Zero

(b) $\frac{\mu_0 n^{2} e}{r}$

(c) $\frac{\mu_0 n e}{2 r}$

(d) $\frac{\mu_0 n e}{2 \pi r}$

[2015]

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Answer:

Correct Answer: 34. (c)

Solution:

  1. (c) Radius of circular orbit $=r$

No. of rotations per second $=n$

i.e., $T=\frac{1}{n}$

Magnetic field at its centre, $B_c=$ ?

As we know, current

$i=\frac{e}{T}=\frac{e}{(1 / n)}=e n=$ equivalent current

Magnetic field at the centre of circular orbit,

$B_c=\frac{\mu_0 i}{2 r}=\frac{\mu_0 n e}{2 r}$