Question

A beam of monochromatic light of wavelength λ ejects photoelectrons from a cesium surface (ϕ = 1.9 eV). These photoelectrons are made to collide with hydrogen atoms in ground state. Find the maximum value of λfor which (a) hydrogen atoms may be ionized, (b) hydrogen atoms may get excited from the ground state to the first excited state and (c) the excited hydrogen atoms may emit visible light.

Answer 1

ϕ= 1.9 eV

a) The hydrogen is ionized

(c) Excited atom will emit visible light if an electron jumps from the second orbit to the third orbit, i.e. from n₁= 2 to n₂= 3. This is because Balmer series lies in the visible region. 

Energy (E₂) of this transition is given by

Comments

What are we suppose to do in part C ma'am?