A voltmeter of resistance 150 Ω connected across a cell of e.m.f. 3 V reads 2.5 V. What is the internal resistance of the cell? (a) 10 Ω (b) 15 Ω (c) 20 Ω (d) 30 Ω

Answer: (d). Current through the voltmeter: I = (2.5)/(150) = 1/60 A Drop across internal resistance = 3 - 2.5 = 0.5 V r = (0.5)/(1/60) = 30 Ω. So the answer is (d) 30 Ω.

A voltmeter of resistance 150 Ω connected across a cell of e.m.f. 3 V… | MHT CET 2023 (10 May, Shift 1)

Q13MHT CET 2023 · 10 MAY · SHIFT 1Easy

Cells: EMF, Internal Resistance & Combinations

A voltmeter of resistance $150\ \Omega$ connected across a cell of e.m.f. $3\text{ V}$ reads $2.5\text{ V}$ . What is the internal resistance of the cell?

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Answer: (d)

Current through the voltmeter: $I = \frac{2.5}{150} = \frac{1}{60}\text{ A}$
Drop across internal resistance $= 3 - 2.5 = 0.5\text{ V}$
$r = \frac{0.5}{1/60} = 30\ \Omega$ . So the answer is (d) $30\ \Omega$ .

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Cells: EMF, Internal Resistance & Combinations question from MHT CET 2023 (10 May, Shift 1)

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