A potentiometer having the potential gradient of 2 mV / cm is use… - Vidyadip

MCQ

A potentiometer having the potential gradient of $2\ \mathrm{mV} / \mathrm{cm}$ is used to measure the difference of potential across a resistance of $10\ \mathrm{ohm}$. If a length of $50 \mathrm{~cm}$ of the potentiometer wire is required to get the null point, the current passing through the $10\ \mathrm{ohm}$ resistor is (in $m A)$

A
$1$
B
$2$
C
$5$
✓
$10$

✓

Answer

Correct option: D.

$10$

$ V=x l \Rightarrow i R=x l $
$ \Rightarrow i \times 10=\left(\frac{2 \times 10^{-3}}{10^{-2}}\right) \times 50 \times10^{-2}=0.1$
$ \Rightarrow i=10 \times 10^{-3} \mathrm{~A}=10 \mathrm{~mA} .$

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