Wavelength, \(\lambda_{1}=5000 \,\,{\mathop {\text{A}}\limits^o }\)

Number of photons emitted per second, \(N_{1}=10^{15}\)

Energy of each photon, \(E_{1}=\frac{h c}{\lambda_{1}}\) 

Power of source \(S_{1}, P_{1}=E_{1} N_{1}=\frac{N_{1} h c}{\lambda_{1}}\)

For a source \(S_{2}\) 

Wavelength, \(\lambda_{2}=5100\,\,{\mathop {\text{A}}\limits^o }\)

Number of photons emitted per second,

\(N_{2}=1.02 \times 10^{15}\)

Energy of each photon, \(E_{2}=\frac{h c}{\lambda_{2}}\)

Power of source \(S_{2},\,\,P_{2}=N_{2} E_{2}=\frac{N_{2} h c}{\lambda_{2}}\)

\(\therefore \,\,\frac{{{\text{ Power of}}\,{\text{ }}{S_2}}}{{{\text{ Power of }}\,{S_1}}} = \frac{{{P_2}}}{{{P_1}}}\) \( = \frac{{\frac{{{N_2}hc}}{{{\lambda _2}}}}}{{\frac{{{N_1}hc}}{{{\lambda _1}}}}} = \frac{{{N_2}{\lambda _1}}}{{{N_1}{\lambda _2}}}\)

\( = \frac{{(1.02 \times {{10}^{15}}{\text{ photons/s) }} \times (5000{\mkern 1mu} {\mkern 1mu} \mathop {\text{A}}\limits^o )}}{{({{10}^{15}}{\text{ photons/s) }} \times (5100{\mkern 1mu} {\mkern 1mu} \mathop {\text{A}}\limits^o )}}\) \( = \frac{{51}}{{51}} = 1\)