APFIVE Voltmeter Loading Effect
A voltmeter with internal resistance $$R_v$$ is used to measure the potential difference across resistor $$R_2$$ in a voltage divider circuit with resistors $$R_1$$ and $$R_2$$ in series. Which expression correctly describes the ratio of the measured voltage $$V_{measured}$$ to the actual voltage $$V_{actual}$$ across $$R_2$$ when the voltmeter is not connected?
A
$$\frac{V_{measured}}{V_{actual}} = \frac{R_v}{R_1 + R_v}$$
B
$$\frac{V_{measured}}{V_{actual}} = \frac{R_v}{R_2 + R_v} \cdot \frac{R_1 + R_2}{R_1 + \frac{R_2 R_v}{R_2 + R_v}}$$
C
$$\frac{V_{measured}}{V_{actual}} = \frac{R_2}{R_2+R_v}$$
D
$$\frac{V_{measured}}{V_{actual}} = \frac{R_v R_2}{(R_v + R_2) R_2}$$
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