JEE Main 25 July 2021 Shift 2 Solved Paper

A light beam of wavelength 500nm is incident on a metal having work function of 1.25eV, placed in a magnetic field of intensity B. The electrons emitted perpendicular to the magnetic field B, with maximum kinetic energy are bent into circular arc of radius 30cm. The value of B is _______ ×10−7T
Given hc=20×10−26J−m, mass of electron=9×10−31kg