A) \[\ell \]
B) \[2\ell \]
C) \[\ell /2\]
D) \[\ell /4\]
Correct Answer: C
Solution :
Balancing length \[l\] will give emf of cell \[\therefore \]\[E=Kl\] Here K is potential gradient. If the cell is short circuited by resistance ?R' Let balancing length obtained be V then\[V=kl'\] \[r=\left( \frac{E-V}{V} \right)R\] \[\Rightarrow \]\[V=E-V\] \[[\because r=R\,\text{given}]\] \[\Rightarrow \]\[V=E-V\]\[\Rightarrow \]\[2V=E\]or\[2Kl'=Kl\] \[\therefore \]\[l'=\frac{l}{2}\]You need to login to perform this action.
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