A galvanometer (coil resistance is converted into an ammeter using a shunt of
and connected as shown in figure -1 . The ammeter reads
.
The same galvanometer is converted into a voltmeter by connecting a resistance of in series. This voltmeter is connected as shown in figure-2. Its reading is found to be
of the full scale reading. The internal resistance of the cell
is
For ammeter
is the full scale deflection current of the galvanometer and
is the range of ammeter
For the circuit in figure-1