Most Important Selected Qs for JEE AdvancedPhysicsDual Nature of Matter
Light from a discharge tube containing hydrogen atoms falls on a piece of sodium due to the transition of electron from 4^ th orbit to 2^ nd orbit. Work function of sodium is 1.83 eV . The fastest moving photoelectron is allowed to enter in a magnetic field, which is perpendicular to the direction of motion of photoelectron as shown in figure. Find distance (in m ) covered by the electron in the magnetic field. [ B =
Correct answer
6
Step-by-step solution
Energy of incident photon =13.6 [ 1 2^2 - 1 4^2 ]=13.6 [ 1 4 - 1 16 ]=13.6 3 16 =2.55 eV Energy of photon = work function (W)+( K.E. )_ Deflection 180^ -60^ =120^ (from geometry) Radius m v^2 R = qvB R = mv / qB circumference of part inside the magnetic field