The hottest thing in physics lovers’ circles these days is not an “artificial sun” or a nuclear power plant, but a light bulb. For this light bulb, the bigwigs on domestic and international social media platforms have launched a debate.
The debate started with a question: In a circuit, the power supply and the switch, 1 meter away from the bulb, but the middle through the two 300,000 km long wire connection, press the switch, how long will the light bulb.
The first was a counterintuitive answer from YouTube’s “Veritasium”, a popular science guru with millions of followers: 1/c s. The reason he gave was that the light bulb does not actually need to be energized by the wire, but only by being connected, and the battery will transmit energy through the electromagnetic field, so the time it takes for the light bulb to receive electricity is simply the distance divided by the speed of light (i.e. 1/c). .
However, ElectroBOOM, EEVBlog, and even the domestic teacher Yongle Li, have questioned this. Among the objections are that the power transmitted through electromagnetic waves is not enough to light up a light bulb; the electric field inside the light bulb wire is not formed, there is no Poincare vector, etc.
The above-mentioned bigwigs have made videos to explain their views, the controversy is fierce, and the views of netizens in the video comment section are also wonderful.
Finally, one of the big names in science, Dr. Brian Haidet, a materials scientist, put an end to the debate. He personally set up the experimental scenario as described in the Element of Truth video, using a 1,000-meter-long wire to connect a power switch to a resistor that replaces the light bulb.
The final results showed that a steady-state current began to pass at the resistor at about 1.6 microseconds, meaning that the current was running along the wire for a distance of about 500m before the bulb was lit.