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科学素养与生活应用·英语30篇(9)

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How Streetlights Know When It’s Getting Dark

How Streetlights Know When It’s Getting Dark

路灯如何感知天色变暗并自动亮起

  1. Streetlights don’t use clocks or timers in most modern cities.
  2. They have tiny light sensors called photoreceptors on top.
  3. When light fades at dusk, the sensor detects less brightness.
  4. Then it sends a signal to turn the lamp on automatically.
  5. At dawn, the same sensor sees more light and switches it off.
  6. This simple tech saves energy and keeps streets safe.
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