Question

Problem4 The work function of chosen metal W 1,5 eV. What is a wavelength A of light irradiated by at its surface when the emitted electrons moving perpendiculary to external homogenous magnetic field of induction B=10-4 T at radius R=5 cm.

Answer 1

Here first of all use Photo equation given by Einstein:

According to this equation if Light if energy E (more than work function of metal) is incident on the surface of metal then electrons get ejected and move with Kinetic energy KE

Equation is given by

E = W + KE

When an electron move perpendicular to the uniform magnetic field then force on electron due to magnetic field given by Bev provides the centripetal force to the electron so that electron traces a circle of radius R given by R = mv/ Be

from this equation we can calculate the velocity needed to trace the given radius. Putting this velocity value into the photo equation the wavelength of radiation by which the metal surface is to be irradiated can be calculated.

Here i have attached a scanned sheet for the detail solution.

Here first of all use Photo equation given by Einstein: According to this equation if Light if energy E (more than work function of metal) is incident on the surface of metal then electrons get ejected and move with Kinetic energy KE Equation is given by E = W + KE When an electron move perpendicular to the uniform magnetic field then force on electron due to magnetic field given by Bev provides the centripetal force to the electron so that electron traces a circle of radius R given by R = mv/Be from this equation we can calculate the velocity needed to trace the given radius. Putting this velocity value into the photo equation the wavelength of radiation by which the metal surface is to be irradiated can be calculated. Here I have attached a scanned sheet for the detail solution. W = work function [minimum energy required to eject electron from surface of metal]