Question

An electron is injected into a uniform magnetic field with components of velocity parallel to and normal to the field direction. The path of the electron is a

A) Helix

B) Parabola

C) Circle

D) Straight line​

Answer 1

If the direction of velocity has both parallel and perpendicular components to the direction magnetic field, the perpendicular component tends to move it in a circle and parallel component tends to move it along the direction of magnetic field. Hence the trajectory is a helix.