An electron $(e)$ moves in a circular orbit of radius '$r$' with uniform speed '$V$'. It produces a magnetic field '$B$' at the center of the circle. The magnetic field $B$ is ($\mu_0 =$ permeability of free space).

• A
  $\frac{\mu_0 e}{4 \pi} \left( \frac{V}{r^2} \right)$
• B
  $\frac{\mu_0 e}{4 \pi} Vr^2$
• C
  $\frac{\mu_0 e}{4 \pi} \left( \frac{V}{r} \right)$
• D
  $\frac{\mu_0 e}{4 \pi} Vr$