ઇલેક્ટ્રોનની તરંગલંબાઇ \(40\, {kV}\)ના પોટેન્શિયલ તફાવત દ્વારા \({X}\, \times\) \(10^{-12} \,{~m}\) સ્થિર અવસ્થાથી વેગ આપે છે.\({x}\)નું મૂલ્ય \(.....\) છે. (નજીકના પૂર્ણાંકમાં) આપેલ છે: ઇલેક્ટ્રોનનું દળ \(=9.1 \times 10^{-31}\, {~kg}\) ઇલેક્ટ્રોનનો વીજભાર \(=1.6 \times 10^{-19}\, {C}\) પ્લાન્ક અચળાંક \(=6.63 \times 10^{-34\,} {Js}\)

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.