Q125 / 200 · NEET 2012 (Screening) · Physics

A millivoltmeter of $25 \mathrm{mV}$ range is to be converted into an ammeter of 25 A range. The value (in ohm) of necessary shunt will be

  • Correct answer
    A
    0.001
  • B
    0.01
  • C
    1
  • D
    0.05

Solution

The full scale deflection current $i_g=\frac{25 \mathrm{mV}}{G} \text { ampere }$ where $G$ is the resistance of the meter. The value of shunt required for converting it into ammeter of range $25 \mathrm{~A}$ is $S=\frac{i_g G}{i-i_g}$ So that, $S \approx \frac{25 \mathrm{mV}}{25}=0.001 \Omega$

Hence, the correct answer is option: 'A'.

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