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In the circuit shown in figure, the ammeter shows \mathrm{5 A} current, voltmeter shows \mathrm{250 V} and the internal resistance of the voltmeter is \mathrm{2500\Omega}, then the value of \mathrm{R} is:

 

Option: 1

150\Omega


Option: 2

0.51\Omega


Option: 3

510\Omega


Option: 4

51\Omega


Answers (1)

best_answer

Current flowing through the voltmeter is\mathrm{I_{v}=\frac{250V}{2500\Omega}=\frac{1}{10}A}

Current flowering through the resistor \mathrm{R} is

\mathrm{I}_{\mathrm{R}}=5 \mathrm{~A}-\frac{1}{10} \mathrm{~A}=\frac{49}{10} \mathrm{~A}

Potential difference across resistance \mathrm{R}$ is $\mathrm{V}_{\mathrm{R}}=250 \mathrm{~V}[\because \mathrm{R} is connected in parallel with voltmeter ]

\therefore \quad \mathrm{R}=\frac{\mathrm{V}_{\mathrm{R}}}{\mathrm{I}_{\mathrm{R}}}=\frac{250 \mathrm{~V}}{\frac{49}{10} \mathrm{~A}}=51 \Omega

Hence option 4 is correct.

Posted by

Divya Prakash Singh

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