\(\therefore \,\,{V_0}\, = \,\,\frac{{hc}}{{\lambda e}}\,\, - \,\,\frac{{hc}}{{{\lambda _0}e}}\)

\(\therefore \,{V_0}\, = \,\,\frac{{hc}}{e}\,\left( {\frac{1}{\lambda }\,\, - \,\,\frac{1}{{{\lambda _0}}}} \right)\)

\(\therefore \,\,4.8\,\, = \,\,\,\frac{{hc}}{e}\,\left( {\frac{1}{\lambda }\,\, - \,\,\frac{1}{{{\lambda _0}}}} \right)\,\,.......\,\,(1)\) અને 

\(\,1.6\,\, = \,\,\frac{{hc}}{e}\,\left( {\frac{1}{{2\lambda }}\,\, - \,\,\frac{1}{{{\lambda _0}}}} \right)\,\,.......\,\,(2)\,\,\)

સમીકરણ \((1)\) અને \((2)\) વડે ભાગતાં

\({\rm{3}}\,\, = \,\,\,\frac{{\left( {\frac{1}{\lambda }\,\, - \,\,\frac{1}{{{\lambda _0}}}} \right)}}{{\left( {\frac{1}{{2\lambda }}\,\, - \,\,\frac{1}{{{\lambda _0}}}} \right)}}\)

\( = \,\,\,\frac{{\frac{{{\rm{(}}{\lambda _{\rm{0}}}\,{\rm{ - }}\,\,\lambda {\rm{)}}}}{{\lambda {\lambda _{\rm{0}}}}}}}{{\frac{{{\rm{(}}{\lambda _{\rm{0}}}\,{\rm{ - }}\,\,{\rm{2}}\lambda {\rm{)}}}}{{{\rm{2}}\lambda \,{\rm{.}}\,\,{\lambda _{\rm{0}}}}}}}\,\,\,\)

\(\therefore \,\,3\lambda \,({\lambda _0}\, - \,\,2\lambda )\,\, = \,\,2\lambda \,({\lambda _0}\, - \,\,\lambda )\)

\(\therefore \,\,3{\lambda _0}\, - \,\,6\lambda \,\, = \,\,2{\lambda _0}\, - \,\,2\lambda \)

\(\therefore \,\,{\lambda _0}\, = \,\,4\lambda \)