• # question_answer Two scales on voltmeter measure voltages up to 20V and 30V. The resistance connected in series with galvanometer is $1680\Omega$ for the 20V scale and $2930\Omega$ for the 30V scale in the same galvanometer. The resistance of the galvanometer and the full scale current are: A) $320\Omega$ and 10 mA B) $70\Omega$ and 10 mA C) $820\Omega$ and 10 mA D) $820\Omega$ and 8 mA

 $\frac{20}{Ig}-1680={{R}_{G}};$ $\frac{30}{Ig}-2930={{R}_{G}}$ $\therefore {{I}_{g}}=8mA$ and ${{R}_{G}}=820\Omega$