ऊर्जा \(E\) का एक इलेक्ट्रॉन किरण पुँज एक लक्ष्य से प्रकीर्णित होता है जिसका परमाणु अन्तराल \(1\, A^૦\) है। प्रथम महत्तम तीव्रता \(\theta=60^{\circ}\) पर प्राप्त होती है। तब \(E\) \(......\,eV\) होगा। (दिया है : प्लांक नियतांक \(h =6.64 \times 10^{-34}\, Js\), \(1 eV =1.6 \times 10^{-19} \,J\) इलेक्टॉन का द्रव्यमान \(m =9.1 \times 10^{-31} \,kg\) )

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.