Question 155 of 200

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 a circular arc of radius $30cm$. The value of $B$ is ________$\times {10}^{-7}T$.
Given $hc=20\times {10}^{-26}Jm$, the mass of the electron$=9\times {10}^{-31}kg$.