द्रव्यमान \(m\) तथा आवेश \(q\) का एक कण पर एक विधुत क्षेत्र \(E ( x )= E _{0}\left(1- ax ^{2}\right)\), जो \(x\)-दिशा में है, लगाया जाता है। यहाँ पर \(a\) तथा \(E _{0}\) स्थिरांक है आरम्भ में कण \(x =0\) पर विरामावस्था में है। प्रारम्भिक अवस्था के अतिरिक्त मूल बिन्दु से कण की किस दूरी पर कण की गतिज ऊर्जा शून्य होगी?

A \(\sqrt{\frac{2}{a}}\)
B \(\sqrt{\frac{1}{a}}\)
C \(a\)
D \(\sqrt{\frac{3}{a}}\)

Verified Solution

Answer & Solution

Correct Answer

(D) \(\sqrt{\frac{3}{a}}\)

Step-by-step Solution

Detailed explanation

\(E = E _{0}\left(1- ax ^{2}\right)\) \(W =\int q E\, d x = q E _{0} \int_{0}^{ x _{0}}\left(1- ax ^{2}\right) dx\) \(=q E_{0}\left[x_{0}-\frac{a x_{0}^{3}}{3}\right]\) For \(\Delta KE =0, \quad W =0\) Hence \(x _{0}=\sqrt{\frac{3}{ a }}\)

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.

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