Question

A potential difference of 220 V is applied across a rheostat of 12000 ohm. The voltmeter V has a resistance of 6000 ohm and point C is at one fourth of the distance from A to B. The error in the reading of voltmeter is approximately –

• A. 26%
• B. 10%
• C. 40%
• D. 15%

Answer 1

Answer: (A)

26%

Answer 2

It total voltage across AB is 220 then voltage across CB should be $\frac{220}{4}$= 54 volts (voltage to be measured)

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V¢ = $\frac{220 \times 2000}{11000}$= 40 V (voltage being measured)

\ % error = $\frac{V - V'}{V}$× 100 = $\frac{54 - 40}{54}$× 100 = 26%