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JEE Main 2014 (12 Apr, Shift 1) · Potentiometer

Potentiometer question from JEE Main 2014 (12 Apr, Shift 1)

Q82JEE Main 2014 · 12 APR · SHIFT 1Medium

Potentiometer

In the experiment of calibration of voltmeter, a standard cell of e.m.f. 1.1 volt is balanced against 440 cm of potentiometer wire. The potential difference across the ends of resistance is found to balance against 220 cm of the wire. The corresponding reading of voltmeter is 0.5 volt. The error in the reading of voltmeter will be:

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Answer: (d)

  1. Potential gradient from the standard cell: k=1.1440=0.0025 V/cmk = \frac{1.1}{440} = 0.0025\ \text{V/cm}.
  2. True p.d. =k×220=0.0025×220=0.55 V= k \times 220 = 0.0025 \times 220 = 0.55\ \text{V}.
  3. Error == voltmeter reading −- true value =0.5−0.55=−0.05 V= 0.5 - 0.55 = -0.05\ \text{V}.
  4. So the answer is (d) −0.05-0.05 V.
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