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MHT CET · Physics · Current Electricity

When moving coil galvanometer (MCG) is converted into a voltmeter, the series resistance is ' \(n\) ' times the resistance of galvanometer. How many times that of MCG the voltmeter is now capable of measuring voltage?

  1. A \(n\)
  2. B \(\frac {n+1}{n}\)
  3. C \(n+1\)
  4. D \(n-1\)
Verified Solution

Answer & Solution

Correct Answer

(C) \(n+1\)

Step-by-step Solution

Detailed explanation

Series resistance is \(\mathrm{n}\) times of galvanometer resistance: \(\mathrm{R}_{\mathrm{s}}=\mathrm{nR}_{\mathrm{G}}\)
Relation between voltage and current:
\(\begin{array}{ll}
\therefore & \mathrm{V}=\mathrm{I}\left(\mathrm{R}_{\mathrm{s}}+\mathrm{R}_{\mathrm{G}}\right) \\
\therefore & \mathrm{V}=\mathrm{I}\left(\mathrm{nR}_{\mathrm{G}}+\mathrm{R}_{\mathrm{G}}\right) \\
\therefore & \mathrm{V}=\mathrm{IR}_{\mathrm{G}}(\mathrm{n}+1)
\end{array}\)
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