A galvanometer $G$ deflects full scale when a potential difference of $0.50 $ $V$ is applied. The internal resistance of the galvanometer $r_g$ is $25$ $ohms$. An ammeter is constructed by incorporating the galvanometer and an additional resistance $R_S$. The ammeter deflects full scale when a measurement of $2.0$ $A$ is made. The resistance $R_S$ is closest to : ................. $\Omega$
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we know to costruct ammeter from galvanometer we add shunt of low reistance in paralle with galvano meter.
$I = i _{ g +} I _{ S }$
$I =2$,
$V$ across $A B=0.50 v$.
$Ig =0.5 / 25=0.02\,V$
$I_{ S }=2-0.02=1.98\,v$
$Rs =0.5 / 1.98=0.252\,V$
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