I know how to do it with ammeter, but how can I find internal resistence without ammeter?
Electronic – How to measure internal resistence of voltmeter without ammeter
internal-resistancemeasurementvoltmeter
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Best Answer
simulate this circuit – Schematic created using CircuitLab
Figure 1. DC voltmeter impedance measurement technique.
For a DC meter such as a typical digital multimeter you can try the scheme of Figure 1.
e.g. If the meter reading falls to half when using a 1M resistor then the resistor must have an input impedance of 1M.
The easiest way to do it is to keep adding or subtracting resistance until you get a reading of half of the battery voltage. That resistance is equal to that of the meter.
Update
No. \$ \frac {meter \ voltage}{total \ voltage} = \frac {meter \ R}{total \ R} \$. So, \$ \frac {VM2}{9} = \frac {Ri}{R1 + Ri} \$.