question_answer

A \[50\,\Omega \]galvanometer is shunted by a resistance of \[5\,\Omega .\] The percentage of the total current,  which  passes  through  the galvanometer is

A)  8.1%  

B)  10.1% 

C)  11.1% 

D)  9.1%

Correct Answer: D

Solution :

 Suppose, G is the resistance of galvanometer and \[{{I}_{g}}\]is the current for full scale deflection. If\[\text{I}\]is the maximum current, then \[{{I}_{g}}\times G=(I-{{I}_{g}})S\] Given. \[G=50\,\Omega \]and \[S=5\,\Omega \] \[\therefore \]\[\frac{{{I}_{g}}}{I}=\frac{S}{G+S}=\frac{5}{50+5}=\frac{5}{55}=\frac{1}{11}\] \[\Rightarrow \] \[{{I}_{g}}=\frac{I}{11}\]or \[\frac{{{I}_{g}}}{I}=\frac{1}{11}\] or \[\frac{{{I}_{g}}}{I}%=\frac{1}{11}\times 100%\approx 9.1%\]