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A voltmeter has a resistance of 100Ω. What will be its reading when it is connected across a cell of e.m.f. 2 V and internal resistance 20Ω? |
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Answer» Given: R = 100Ω, r = 20, E = 2 V To find: Reading of voltmeter (V) Formula: V = E - Ir Calculation: Current through the circuit is given by I = \(\frac{E}{R+r}=\frac{2}{100+20}=\frac{2}{120}\) ∴ I = \(\frac{1}{60} A\) From formula, V = 2 - (\(\frac{1}{60} \times20\)) =2 - 0.3333 ∴ V = 1.667 V Ans: The reading on the voltmeter is 1.667 V. |
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