JEE MAIN - Physics (2023 - 6th April Evening Shift - No. 24)
As shown in the figure, the voltmeter reads $$2 \mathrm{~V}$$ across $$5 ~\Omega$$ resistor. The resistance of the voltmeter is _________ $$\Omega$$.
_6th_April_Evening_Shift_en_24_1.png)
Answer
20
Explanation
$$
i_1=\frac{2 V}{5 \Omega}=\frac{2}{5} \mathrm{~A}
$$
_6th_April_Evening_Shift_en_24_2.png)
$$ i=\frac{1 V}{2 \Omega}=\frac{1}{2} A $$
$\therefore$ Current through voltmeter $=i-i_1$
$$ =\frac{1}{2}-\frac{2}{5}=\frac{5-4}{10}=\frac{1}{10} \mathrm{~A} $$
$\therefore$ For voltmeter
$$ 2=\left(\frac{1}{10}\right) R \Rightarrow R=20 \Omega $$
$$ i=\frac{1 V}{2 \Omega}=\frac{1}{2} A $$
$\therefore$ Current through voltmeter $=i-i_1$
$$ =\frac{1}{2}-\frac{2}{5}=\frac{5-4}{10}=\frac{1}{10} \mathrm{~A} $$
$\therefore$ For voltmeter
$$ 2=\left(\frac{1}{10}\right) R \Rightarrow R=20 \Omega $$
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