Current measurement

Ammeter

Measurement with an ammeter

Current meters are connected in series to the part of the circuit in which the current is to be measured. We increase the range of the ammeter by n-times if we place a resistance (n-1) times smaller than its own resistance in parallel in the circuit.

Compensation method

We can also perform the measurement using the the compensatory method: instead of the meter, we connect a certain known resistance, which reduces the voltage, which we measure with the help of a compensator and calculate the current value from the relation R=U/I. We measure very small currents using a galvanometer (sensitivity up to 10-10A).


Source