બે સમાન \(emf\) ધરાવતા પરંતુ જુદો જુદો \(r_{1}\) અને \(r_{2}\) આંતરિક અવરોધ ધરાવતા બે કોષોને અવરોધ \(R\) સાથે શ્રેણીમાં જોડવામાં આવેલાં છે. જેનાં માટે બીજા કોષને સમાંતર સ્થિતિમાનનો તફાવત શૂન્ય થાય તે અવરોધ \(R\) નું મૂલ્ચ .......થશે.

A \(r _{2}- r _{1}\)
B \(r_{1}-r_{2}\)
C \(r _{1}\)
D \(r _{2}\)

Verified Solution

Answer & Solution

Correct Answer

(A) \(r _{2}- r _{1}\)

Step-by-step Solution

Detailed explanation

\(I=\frac{2 E }{R+I_{1}+I_{2}} \ldots \text{(i)}\) But \(V _{ A }- V _{ B }= E - I _{2}=0\) \(\Rightarrow I =\frac{ E }{ I _{2}} \ldots \text{(ii)}\) Comparing values of \(I\) from \((i)\) and \((ii)\) \(\frac{E}{r_{2}}=\frac{2 E}{R+r_{1}+r_{2}}\) \(\Rightarrow R=r_{2}-r_{1}\)

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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