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KCET · Physics · Magnetic Effects of Current

A moving coil galvanometer is converted into an ammeter of range 0 to \(5 \mathrm{~mA}\). The galvanometer resistance is \(90 \Omega\) and the shunt resistance has a value of \(10 \Omega\). If there are \(\mathbf{5 0}\) divisions in the galvanometer-turned-ammeter on either sides of zero, its current sensitivity is

  1. A \(2 \times 10^4 \mathrm{div} / \mathrm{A}\)
  2. B \(1 \times 10^5 \mathrm{~A} / \mathrm{div}\)
  3. C \(2 \times 10^4 \mathrm{~A} / \mathrm{div}\)
  4. D \(1 \times 10^5 \mathrm{div} / \mathrm{A}\)
Verified Solution

Answer & Solution

Correct Answer

(D) \(1 \times 10^5 \mathrm{div} / \mathrm{A}\)

Step-by-step Solution

Detailed explanation

Given, \(S=10 \Omega\)
\(\begin{aligned} & G=90 \Omega \\ & i=5 \times 10^{-3} \mathrm{~A}\end{aligned}\)
Number of divisions on one side of zero \(=50\)
\(i_g=\frac{S}{S+G} \times i=\left(\frac{10}{90+10}\right)\left(5 \times 10^{-3}\right)=5 \times 10^{-4} \mathrm{~A}\)
Number of divisions per unit current \(=\frac{50}{5 \times 10^{-4}}\) \(=1 \times 10^{-5} \mathrm{div} / \mathrm{A}\)