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

• A

  $\frac{{\mathrm{\mu }}_0\mathrm{n}\mathrm{e}}{2\mathrm{\pi }\mathrm{r}}$
• B

  Zero
• C

  $\frac{{\mathrm{\mu }}_0{\mathrm{n}}^2\mathrm{e}}{\mathrm{r}}$
• Correct answer
  D

  $\frac{{\mathrm{\mu }}_0\mathrm{n}\mathrm{e}}{2\mathrm{r}}$

Hence, the correct answer is option: 'D'.