A potentiometer wire of length $1\,m$ and resistance $10\,\Omega$ is connected in series with a cell of $emf$ $2\,V$ with internal resistance $1 \,\Omega$ and a resistance box including a resistance $R$. If potential difference between the ends of the wire is $1\, mV$, the value of $R$ is ............. $\Omega $
Medium
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(b) $V = i.R{\rm{. }} = \frac{e}{{(R + {R_h} + r)}}\,.\,R \Rightarrow {10^{ - 3}} = \frac{2}{{(10 + R + r)}} \times 10$
$ \Rightarrow $ $R$$ = 19,989\,\Omega $.
$ \Rightarrow $ $R$$ = 19,989\,\Omega $.
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