\( \Rightarrow \,\,\frac{{hc}}{\lambda }\,\, = \,\,\,e\,{V_0} + \,\,\phi \,\,\,.....\,\,(i)\,\) અને
\(\frac{{hc}}{{\lambda '}}\,\, = \,\,\,e\,V'_0\,\, + \,\,\phi \).........(ii)
આથી \(, \,\,\frac{{hc}}{{\lambda'}} - \, \frac{{hc}}{\lambda }\,\, = \,\,eV'_0\,\, - \,\,e{V_0}\,\, = \,\,e\,(V'_0\, - \,{V_0})\,\,\)
\( \Rightarrow \,\,\frac{{12400\,\,eV\,\mathop A\limits^ \circ }}{{4272\,\mathop A\limits^ \circ }}\, - \)
\( - \,\,\frac{{12400\,\,eV\,\mathop A\limits^\circ }}{{6402\,\,\mathop A\limits^ \circ }}\,\, = \) \(e\,(V'_0\, - \,{V_0})\)
\( \Rightarrow \,\,\,\,2.91\,\,eV\, - \,\,1.94\,\,eV\, = \,\,e\,(V'_0 - {V_0})\,\)
\(\, \Rightarrow \,\,V'_0\, = \,\,097\,\,V\,\, + \,\,0.54\,\,V\,\, = \,\,1.51\,\,\,V\)