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JEE Main 2019 (12 Jan, Shift 2) · Kirchhoff's Laws & Measuring Instruments

Kirchhoff's Laws & Measuring Instruments question from JEE Main 2019 (12 Jan, Shift 2)

Q167JEE Main 2019 · 12 JAN · SHIFT 2Medium

Kirchhoff's Laws & Measuring Instruments

A galvanometer, whose resistance is 50 ohm, has 25 divisions in it. When a current of 4 ×\times 10–4 A passes through it, its needle ( pointer) deflects by one division. To use this galvanometer as a voltmeter of range 2.5 V, it should be connected to a resistance of:

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Answer: (a)

  1. Full scale current Ig=25×4×10−4=10−2 AI_g = 25 \times 4\times10^{-4} = 10^{-2}\text{ A}
  2. Series resistance R=VIg−G=2.50.01−50R = \frac{V}{I_g} - G = \frac{2.5}{0.01} - 50
  3. R=250−50=200 ΩR = 250 - 50 = 200\ \Omega
  4. So the answer is (a) 200 ohm.
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