Steps to measure current with a multimeter
1. Select the range: The DC current range of the multimeter is marked with "mA", and there are three ranges: 1mA, 1omA, and 100mA. The range should be selected according to the current in the circuit.
2. Measurement method: The multimeter should be connected in series with the circuit under test. After disconnecting the corresponding part of the circuit, connect the multimeter leads to both ends of the breakpoint. The red test lead should be connected to the breakpoint connected to the positive pole of the power supply, and the black test lead should be connected to the breakpoint connected to the negative pole of the power supply.
1) Connect the circuit so that the light-emitting diodes glow normally.
2) Before use, it is required to prepare the multimeter and set the selection switch to the mA range of 100mA.
3) Disconnect the lead wire between the junction point of the potentiometer and the negative electrode of the light-emitting diode to form a "breakpoint".
4) Connect the multimeter in series to 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.
5) Correctly read the current value through the LED. Record: The current through the LED is xx mA.
6) Turn the handle of the potentiometer to observe the changes of the pointer of the multimeter and the brightness of the LEDs.
8) Through the above operations, you can further understand the role of resistors in the circuit.
9) After the measurement, disconnect the power supply and put away the multimeter as required.
