Far three near two, if it is a high beam, dial it three times, if it is a low beam, dial it twice, and finally become a low beam. These two kinds of lights are used for night lighting, but the high beam has a large angle and a long distance, while the low beam has a small angle and a short distance. 3. In addition, although the irradiation distance of the low beam lamp is about 30 meters, it has a very obvious beam cutoff line. The irradiation distance of most of the low beam lamps we measure is 30-40m, and the cutoff line of the beam is about12m-18m.
light source
1860, Swan invented the prototype semi-vacuum carbon filament lamp of incandescent lamp. 1875, Swan improved his invention. In the late 1970s, vacuum technology had developed to the required level, and Edison was also doing research. Finally, the two men made practical incandescent lamps almost at the same time. Edison, as always, was more active in obtaining patents. 1878, Swan patented the incandescent lamp one year earlier than Edison.