JEE Mains · Physics · STD 12 - 4. Moving charges and magnetism
A galvanmeter has a coil of resistance \(200 \Omega\) with a full scale deflection at \(20 \mu \mathrm{A}\). The value of resistance to be added to use it as an ammeter of range \((0-20) \mathrm{mA}\) is _______.
- A \(0.40 \Omega\)
- B \(0.20 \Omega\)
- C \(0.50 \Omega\)
- D \(0.10 \Omega\)
Answer & Solution
Correct Answer
(B) \(0.20 \Omega\)
Step-by-step Solution
Detailed explanation
\(\mathrm{G}=200 \Omega\) \(\mathrm{i}_{\mathrm{g}}=20 \mu \mathrm{A}\) \(\mathrm{i}=\mathrm{i}_{\mathrm{g}}\left(\frac{\mathrm{G}}{\mathrm{S}}+1\right)\) \(\Rightarrow 20 \times 10^{-3}=20 \times 10^{-6}\left(\frac{200}{\mathrm{~S}}+1\right)\)…
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