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AP EAMCET · PHYSICS · Current Electricity

A galvanometer has a coil of resistance \(100 \Omega\) showing a full scale deflection at \(50 \mu \mathrm{A}\). The resistance that should be added to use it as an ammeter of range \(10 \mathrm{~mA}\) is

  1. A \(5 \Omega\)
  2. B \(5 \times 10^{-2} \Omega\)
  3. C \(0.5 \Omega\)
  4. D \(1 \Omega\)
Verified Solution

Answer & Solution

Correct Answer

(C) \(0.5 \Omega\)

Step-by-step Solution

Detailed explanation

Given, Resistance of galvanometer \[ \begin{aligned} R_g & =100 \Omega \\ I_g & =50 \mu \mathrm{A}=5 \times 10^{-5} \mathrm{~A} \\ I & =10 \mathrm{~mA}=10^{-2} \mathrm{~A} \\ R_s & =? \end{aligned} \] We know that, \[ R_s=\frac{I_g}{I-I_g} \times R_g . \]…