JEE Main 2025 — 2 April, Morning Shift — Question 59

A monochromatic light is incident on a metallic plate having work function $\phi$. An electron, emitted

normally to the plate from a point $A$ with maximum kinetic energy, enters a constant magnetic field, perpendicular to the initial velocity of electron. The electron passes through a curve and hits back the

plate at a point $B$. The distance between $A$ and $B$ is: (Given: The magnitude of charge of an

electron is $e$ and mass is $m, h$ is Planck's constant and $c$ is velocity of light. Take the magnetic

field exists throughout the path of electron)