An ideal ammeter has zero resistance so that the
the circuit in which it has been placed is not disturbed.
An ideal ammeter is a short circuit.
However, as with the voltmeter, no ammeter
can ever be ideal, and therefore all ammeters have some ( hopefully) small
internal resistance.
To determine the resistance of the ammeter, we will use the circuit
in Figure 
.
According to Ohm's Law, the current in this circuit will be 
where 
. So the current can be found using the equation:
By using the known quantities 
and R, we can solve for the unknown quantity
.
In the procedure that follows it is extremely important that you take precise and accurate measurements. Record each measurement as precisely as the instrument will allow.
resistor. Measure and record its actual value.
. Set the multimeter to the ammeter mode
for dc current measurement. Recall this means two things: Place the test leads in the
correct banana jacks and press the proper sequence of softkeys.
from Equation .
