Measure resistance with voltmeter and ammeter 1. Measure the resistance of the small light bulb when it normally emits light by voltammetry (only once) 2. Adjust the sliding rheostat to make the small bulb glow under the rated voltage 3. Fill the measured value in the table and calculate the resistance Laboratory equipment: There are 3 dry batteries, 1 switch, 1 voltmeter, 1 current expression, 1 sliding rheostat (20 Ω), 1 small bulb (3.8V) and dry root of wire

Measure resistance with voltmeter and ammeter 1. Measure the resistance of the small light bulb when it normally emits light by voltammetry (only once) 2. Adjust the sliding rheostat to make the small bulb glow under the rated voltage 3. Fill the measured value in the table and calculate the resistance Laboratory equipment: There are 3 dry batteries, 1 switch, 1 voltmeter, 1 current expression, 1 sliding rheostat (20 Ω), 1 small bulb (3.8V) and dry root of wire

1. Connect the voltmeter to both ends of the small bulb in parallel
2. Connect the circuit, connect the ammeter and sliding rheostat into the circuit in turn
3. Move the slide to make the small bulb light normally (at this time: the voltage indication is 3.8V), count the current indication, the voltage indication I, U
4. Small bulb resistance R = u / I