A) 0.25 A
B) 0.8 A
C) 0.2 A
D) 0.5 A
Correct Answer: B
Solution :
Key Idea: Potential difference across galvanometer should be equal to potential difference across shunt. The shunt and galvanometer are connected as shown in figure. Let total current through the parallel combination is \[i,\]the current through the galvanometer is \[{{i}_{g}}\]and the current through the shunt is\[i-{{i}_{g}}.\] The potential difference \[{{V}_{ab}}(={{V}_{a}}-{{V}_{b}})\]is the same for both paths, so \[{{i}_{g}}G=(i-{{i}_{g}})S\] or \[{{i}_{g}}(G+S)=i\,S\] or \[\frac{{{i}_{g}}}{i}=\frac{S}{S+G}\] The fraction of current passing through shunt \[=\frac{i-{{i}_{g}}}{i}=1-\frac{{{i}_{g}}}{i}\] \[=1-\frac{S}{S+G}=\frac{G}{S+G}\] \[=\frac{8}{2+8}=\frac{8}{10}\] \[=0.8\,A\]You need to login to perform this action.
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