A moving coil of galvanometer when shunted with resistance gives a full-scale deflection for a current of 500 mA

Question

A moving coil of galvanometer when shunted with $2 Ω$ resistance gives a full-scale deflection for a current of 500 mA. When a resistance of 470 $Ω$ is connected in series, it gives a full-scale deflection for 10 V potential is applied on it. The value of resistance of galvanometer coil is _____ $Ω$ . [2026]

Smart Achievers · Accepted Answer

(50)

$Ω$

$I = 500 mA = 0.5 A$

$Current through galvanometer$

$I_{g} = I (\frac{S}{G + S}) = 0.5 (\frac{2}{G + 2})$

$V = 10 V, R = 470$

$\Rightarrow V = I_{g} (G + R)$

$\Rightarrow 10 = \frac{1}{G + 2} (G + 470)$

$\Rightarrow 10 G + 20 = G + 470$

$\Rightarrow 9 G = 450 = 50 Ω$

Solution

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Solution

Ans. (50) Total current for full scale deflection I=500 mA=0.5 A Current through galvanometer Ig=I(SG+S)=0.5(2G+2) V=10 V, R=470 ⇒V=Ig(G+R) ⇒10=1G+2(G+470) ⇒10G+20=G+470 ⇒9G=450=50 Ω

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