A cell of internal resistance is connected across a resistor. A voltmeter having variable resistance G is used to measure potential difference across resistor. The plot of voltmeter reading V against G is shown. What is value of external resistor R ?

Question

A cell of internal resistance is connected across a resistor. A voltmeter having variable resistance G is used to measure potential difference across resistor. The plot of voltmeter reading V against G is shown. What is value of external resistor R ? (A) 5 Ω (B) 4 Ω (C) 3 Ω (D) 1 Ω

Tardigrade Admin · Accepted Answer

When G=∞, V=20 V and no current will pass through voltmeter. <img class="img-fluid question-image" alt="image" src="https://cdn.tardigrade.in/img/question/physics/954444f03af86b90636eaa99fd24e0a8-.png" /> I=(4/1)=4 A ; R=(20/I)=(20/4)=5 Ω

Q. A cell of internal resistance is connected across a resistor. A voltmeter having variable resistance $G$ is used to measure potential difference across resistor. The plot of voltmeter reading $V$ against $G$ is shown. What is value of external resistor $R ?$

$5 Ω$

$4 Ω$

$3 Ω$

$1 Ω$

When $G = \infty, V = 20 V$ and no current will pass through voltmeter.

$I = \frac{4}{1} = 4 A; R = \frac{20}{I} = \frac{20}{4} = 5 Ω$

Q. A cell of internal resistance is connected across a resistor. A voltmeter having variable resistance G is used to measure potential difference across resistor. The plot of voltmeter reading V against G is shown. What is value of external resistor R?

5Ω

4Ω

3Ω

1Ω