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  • A voltmeter having a resistance of 1800 is employed to measure the potential difference across 200<img alt="\

A voltmeter having a resistance of 1800\Omega is employed to measure the potential difference across 200\Omega resistance which is connected to dc power supply of 50V and internal resistance 20\Omega. What is the approximate percent change in the P.D  across 200\Omega resistance as a result of connecting the voltmeter across it?

Option: 1

2.2%


Option: 2

5%


Option: 3

1


Option: 4

20%


Answers (1)

best_answer
Solutions 

Let V1 and V2 be the voltage across 200 \Omega resistor before and after connecting the current respectively

 V_1=V-i_1r= 50-50\left (\frac{ 20}{220} \right )=45.45

V_2=V-i_1r=50-50\left (\frac{20 }{200} \right )=45

Percentage change=\frac{V_1-V_2}{V_1} \times 100\%  =1%

 

 

Posted by

sudhir.kumar

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