• # question_answer A moving coil galvanometer is converted into an ammeter reading up to 0.03 A by connecting a shunt of resistance 4r across it. and into an ammeter reading up to 0.06 A when a shunt of resistance r is connected across it. What is the maximum current which can be sent through this galvanometer if no shunt is used? A)  0.01 A                                   B)  0.02 A C)  0.03 A                                   D)  0.04 A

For an ammeter $\frac{{{i}_{g}}}{i}=\frac{S}{G+S}$ $\Rightarrow$               ${{i}_{g}}G=(i-{{i}_{g}})S$ $\therefore$  ${{i}_{g}}G=(0.03-{{i}_{g}})4r$ ???(i) and        ${{i}_{g}}G=(0.06-{{i}_{g}})r$    ...(ii)    From Eqs. (i) and (ii)                   $0.12-4{{i}_{g}}=0.06-{{i}_{g}}$  $\Rightarrow$         ${{i}_{g}}=0.02A$