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CBSE Class 12-science Answered

how to find range of galvanometer when current and resistance is given  
Asked by krvrvijai | 27 May, 2019, 02:05: PM
answered-by-expert Expert Answer
The galvanometer are sensitive and give large deflection when small amount of current passes thorugh it. To avoid the excess flow of current through it so as to prevent the damage of the other electrical instruments, the low resistance is connected in parallel to the galvanometer. This resistance is called shunt resistance. 
So if G is the reistance of the galvanometer and S is the shunt resistance then the total current divides in two parts i.e Ig and Is where Ig is the current range of galvanometer and Is is the current flowing through shunt.
As potential difference  at end of galvanometer and shunt is same,
S = G Ig/Is 
The total current I i.e. current range of ammeter is,
I = Ig + Is 
Thus, Is  = I - Ig 
S space equals G space fraction numerator I subscript g over denominator I space minus space I subscript g end fraction
I subscript g space equals space fraction numerator S over denominator G plus S end fraction. space I 
In this way , the current range of galvanometer can be calculated if resistance and current is known. 
Answered by Shiwani Sawant | 28 May, 2019, 12:07: PM
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