JEE Mains · Physics · STD 12 - Moving charges and magnetism
- JEE Mains 2019
- Medium
- Numerical
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.......\(ohm\)
Pick an option to check your answer.
Answer & Solution
Correct Answer
(B) \(200\)
Step-by-step Solution
Detailed explanation
\({{\text{V}}_{\text{o}}} = {{\text{i}}_{{{\text{g}}_0}}}\left( {{{\text{R}}_{\text{G}}} + {\text{R}}} \right)\)
\({{\text{i}}_{{g_0}}} = 4 \times {10^{ - 4}} \times 25 = {10^{ - 2}}{\mkern 1mu} {\text{A}}\)
\(\mathrm{V}_{0}=2.5\, \mathrm{V}\)
\(R_{0}+R=\frac{V_{0}}{i_{0}}=\frac{2.5}{10^{-2}}=250\)
\(\Rightarrow \quad \mathrm{R}=200\, \Omega\)
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