Consult your owner’s manual on the particular model of meter you own for details on measuring current. When an ammeter is placed in series with a circuit, it ideally drops no voltage as current goes through it. In other words, it acts very much like a piece of wire, with very little resistance from one test probe to the other.
If the ammeter is accidentally connected across a substantial voltage source, the resultant surge in current will blow the fuse and render the meter incapable of measuring current until the fuse is replaced. Be very careful to avoid this scenario!
In other words, it acts very much like a piece of wire, with very little resistance from one test probe to the other. Since an ammeter has very little resistance, it will act as a short circuit if placed in parallel (across the terminals of) a substantial voltage source.
Since an ammeter has very little resistance, it will act as a short circuit if placed in parallel (across the terminals of) a substantial voltage source. If this is done, a surge in current will result, as shown in Figure 2, potentially damaging the meter. Figure 2. Ammeter short circuit connection resulting in a surge current.
The schematic diagram for measuring the current of the lamp circuit using an ammeter. Step 3: Verify that the lamp lights up before connecting the ammeter in series with it. Step 4: Break the circuit open, as illustrated in Figures 1 and 3, and connect the ammeter’s test probes to the two points of the break to measure current.
For a 6 V battery and a small lamp, the circuit current will be in the range of thousandths of an amp or milliamps (mA). Digital meters often show a small letter “m” on the right-hand side of the display to indicate this metric prefix. Step 5: Try breaking the circuit at some other point and inserting the ammeter there instead.