જો \(m\) અને \(e\) એ હાઈડ્રોજન પરમાણુ માટે \(r\) ત્રિજ્યાની ક્ક્ષામાં ફરતા ઇલેક્ટ્રોનના દળ અને વીજભાર હોય તો ફરતા ઇલેક્ટ્રોનની કુલ ઊર્જા શુ થશે ?

A \(\frac{1}{2}\,\frac{{{e^2}}}{r}\)
B \( - \frac{{{e^2}}}{r}\)
C \(\frac{{m{e^2}}}{r}\)
D \(-\frac{1}{2}\,\frac{{{e^2}}}{r}\)

Verified Solution

Answer & Solution

Correct Answer

(D) \(-\frac{1}{2}\,\frac{{{e^2}}}{r}\)

Step-by-step Solution

Detailed explanation

Total energy of a revolving electron is the sum of its kinetic and potential energy. Total energy \(= K.E. + P. E.\) \( = \frac{{{e^2}}}{{2r}} + \left( { - \frac{{{e^2}}}{r}} \right) = - \frac{{{e^2}}}{{2r}}\)

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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