Question

Write Biot-Savart law.
Write the path of motion of an electron when it enters in magnetic field at
(a) perpendicular
(b) an angle $\theta$.

Answer 1

The Biot-Savart Law relates magnetic fields to the currents which are their sources. It is given as

$d\overrightarrow{B}=\frac{{\mu }_0}{4\pi }\frac{\overrightarrow{dl}\times \overrightarrow{I}}{r^2}$

(a) For electron moving perpendicular to magnetic field, the path is circular.

(b) For electron moving angle $\theta$ to magnetic field, the path is helical.