Figure 1 Experimental Scene
Recently, the author has been using Phyphox and ESP32 to capture the current changes when a light bulb is turned on. However, the current change at the moment the light bulb is turned on is quite rapid, making it difficult to draw an ideal current change graph.
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Analysis of Question 16 from the 2021 Beijing Ordinary High School Academic Level Examination Physics Paper
Using Phyphox to capture the current changes at the moment the light bulb is turned on in Question 16 of the 2021 Beijing Ordinary High School Academic Level Examination Physics Paper
Figure 2 At Higher Operating Voltage
Initially, the author attempted to increase the signal sampling frequency of the ESP32, but given that Phyphox’s sampling frequency is not very high, the experimental results did not show significant improvement.
Figure 3 Experimental Scene
After numerous repetitions and failures, the author suddenly realized that if the voltage across the light bulb is higher, the electrical power of the bulb is greater, and the transition time from the circuit being connected to the bulb emitting stable light is shorter, making it harder to capture the current change pattern.
Conversely, if the voltage across the light bulb is lower, the electrical power of the bulb is smaller, and the transition time from the circuit being connected to the bulb emitting stable light is longer, making it easier to capture the current change pattern.
Thus, the author connected the circuit and slowly increased the power supply voltage from the minimum until the bulb emitted a faint light; then disconnected the circuit, allowed the bulb to cool for a while, and ran the program to collect current data. When the circuit was suddenly connected, the combination of ESP32 and Phyphox ideally plotted the current change graph at the moment the light bulb was powered on.
Figure 4 At Low Operating Voltage
By comparing Figure 2 and Figure 4, it can be found that when studying the current change pattern at the moment the light bulb is turned on, it is necessary to capture the current change with the combination of ESP32 and Phyphox at low voltage.