The resistance of a galvanometer is $50\:ohm$ and the maximum current which can be passed through it is $0.002\:A$  . What resistance must be connected to it in order to convert it into an ammeter of range $0-0.5\:A$ ? Option 1) $0.5\:\:ohm$ Option 2) $0.002\:\:ohm$ Option 3) $0.02\:\:ohm$ Option 4) $0.2\:\:ohm$

S solutionqc

For converting galvanometer into ammeter we must add a short resistance

$I_{g}=\frac{I\:S}{G+S}$

Given,

$I_{g}=0.002\:A$

$I=0.5\:A$

$G=50\: \Omega$

$\Rightarrow0.002=\frac{0.5\:S}{50+S} \approx \frac{S}{100}$

$\Rightarrow S=0.2\:\Omega$

Option 1)

$0.5\:\:ohm$

Option 2)

$0.002\:\:ohm$

Option 3)

$0.02\:\:ohm$

Option 4)

$0.2\:\:ohm$

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