A voltmeter is connected across a battery of emf 12 V and internal resistance of 10 Ω. If the voltmeter resistance is 230 Ω, what reading
A voltmeter is connected across a battery of emf 12 V and internal resistance of 10 Ω. If the voltmeter resistance is 230 Ω, what reading will be shown by the voltmeter?
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Given: E = 12 volt, r = 10 Ω, R = 230 Ω
To find: Reading shown by voltmeter (V)
Formula: i. I = \(\frac{E}{R+r}\)
ii. V = E – Ir
Calculation:
From formula (i),
I = \(\frac{12}{230+10}=\frac{12}{240}=\frac{1}{20}\) A
From formula (ii),
V= 12 – \(\frac{1}{20}\) × 10 = 12 – 0.5
= 11.5 volt
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