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Standard XII

Physics

Kirchoff's Voltage Law

A cell of int...

Question

A cell of internal resistance $1 Ω$ is connected across a resistor. A voltmeter having variable resistance G is used to measure p.d across resistor. The plot of voltmeters reading V against G is shown. What is value of external resistor R (in ohm)?

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Solution

As per the graph
When $G = \infty$ then voltage across R as well as lower branch is 20 volt and voltage across $1 Ω$ is 4 volt.
$∵ V = I R$
p.d. across both branch is same, i.e. 20 volts
assume potential across 1 ohm resistor
$24 - x = 20$
$x = 4 v o l t s$

in lower branch, potential across 1 ohm resistor must be 4 volt then only the potential across the lower branch will be equals to 20 volt.

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A cell of internal resistance 1Ω is connected across a resistor. A voltmeter having variable resistance G is used to measure p.d across resistor. The plot of voltmeters reading V against G is shown. What is value of external resistor R (in ohm)? ___

A cell of internal resistance $1 Ω$ is connected across a resistor. A voltmeter having variable resistance G is used to measure p.d across resistor. The plot of voltmeters reading V against G is shown. What is value of external resistor R (in ohm)?

___