A galvanometer of resistance $G$ is converted into a voltmeter to measure upto $V$ volts by connecting a resistance $R_1$ in series with the coil. If a resistance $R_2$ is connected in series with it, then it can measure upto $\raisebox{1ex}{$V$}\!\left/ \!\raisebox{-1ex}{$2$}\right.$ volts. Find the resistance, in terms of $R_1$ and $R_2$, required to be connected to convert it into a voltmeter that can read upto $2 V$. Also find the resistance $G$ of the galvanometer in terms of $R_1$ and $R_2$.