Q.

An electron with kinetic energy 5 eV enters a region of uniform magnetic field of 3 μT perpendicular to its direction. An electric field E is applied perpendicular to the direction of velocity and magnetic field. The value of E, so that the electron moves along the same path, is ____ NC-1. (Given, mass of electron =9×10-31 kg, electric charge =1.6×10-19C)                         [2024]


Ans.

(4)            For the given condition of moving undeflected, net force should be zero.

                qE=qVBE=VB

                E=2×KEm×B=2×5×1.6×10-199×10-31×3×10-6=4 N/C