7 steps to measure DC current with a multimeter
(1) Connect the circuit so that the light-emitting diodes emit light normally.
(2) Prepare the multimeter according to the pre-use requirements mentioned above and set the selection switch to the mA range of 100mA.
3) Disconnect the lead wire between the middle contact point of the potentiometer and the negative electrode of the light-emitting diode to form a "breakpoint". At this time, the LED goes out.
(4) Connect the multimeter in series at the breakpoint. The red test lead is connected to the negative pole of the light-emitting diode, and the black test lead is connected to the middle contact lead of the potentiometer. At this time, the light emitting diode lights up again. The scale value pointed by the pointer of the multimeter is the current value passing through the light-emitting diode.
(5) Correctly read the current value passing through the light-emitting diode.
Note: The current through the LED is mA.
Through the above operations, we can further understand the role of resistors in the circuit.
(6) Rotate the handle of the potentiometer to observe the change of the pointer of the multimeter and the change of the brightness of the light-emitting diode. It can be seen that:
For the record: The maximum current through the LED is mA. The minimum current is mA.
(7) After the measurement is completed, disconnect the power supply and put away the multimeter as required.
