A wire of length $100\, cm$ is connected to a cell of $emf$ $2\, V$ and negligible internal resistance. The resistance of the wire is $3\, \,\Omega$. The additional resistance required to produce a potential drop of $1$ milli volt per cm is ............... $\Omega $
Medium
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(c) Potential gradient $x = \frac{e}{{(R + {R_h} + r)}}.\frac{R}{L}$
$ \Rightarrow \,\,\,\,\,\,\frac{{{{10}^{ - 3}}}}{{{{10}^{ - 2}}}} = \frac{2}{{(3 + {R_h} + 0)}} \times \frac{3}{1} \Rightarrow {R_h} = 57\,\Omega $.
$ \Rightarrow \,\,\,\,\,\,\frac{{{{10}^{ - 3}}}}{{{{10}^{ - 2}}}} = \frac{2}{{(3 + {R_h} + 0)}} \times \frac{3}{1} \Rightarrow {R_h} = 57\,\Omega $.
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