By connecting a resistance of $980\ \Omega$ in series with a galvanometer, it is converted into a voltmeter of a certain range. When the resistance of $470\ \Omega$ is connected in series, the range is halved. The resistance of the galvanometer is

A current of 9A enters point P of an equilateral triangle PQR having three wires of $3\Omega$ each and leaves by point R. The currents $I_1$ and $I_2$ are respectively

In the following figure, the current I is equal to

With a resistance '$X$' connected in series with a galvanometer of resistance $100\ \Omega$, it acts as a voltmeter of range 0 - 15 V. To double the range, a resistance of $1500\ \Omega$ is to be connected in series with '$X$'. The value of '$X$' in $\Omega$ is