question_answer

A galvanometer has 30 divisions and a sensitivity 16\[\mu A/\text{div}\text{.}\]It can be converted into a voltmeter to read 3 V by connecting                                 [Kerala PMT 2005]

A)         Resistance nearly 6 \[k\,\Omega \]in series

B)         \[6\,k\,\Omega \] in parallel

C)         \[500\,\Omega \] in series

D)          It cannot be converted

Correct Answer: A

Solution :

                                         \[(R+G)\,{{i}_{g}}=V\] Þ \[(R+G)=\frac{V}{{{i}_{g}}}\]                    \[=\frac{3}{30\times 16\times {{10}^{-6}}}=6.25k\Omega \]                    \[\therefore \] Value of \[R\] is nearly equal to \[6k\Omega \] This is connected in series in a voltmeter.