प्लेटिनम धातु के साथ प्रकाश विद्युत प्रभाव उत्पन्न करने के लिए फोटोन के पास जो न्यूनतम ऊर्जा होनी चाहिए वह \(....\,\times 10^{-19} \,J\) है।
[दिया गया है : प्लेटिनम की देहली आवृति \(1.3 \times 10^{15} s ^{-1}\) एवं \(h =6.6 \times 10^{-34}\,J\,s.\)]

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.