STEM与日常科技·英语30篇（2）

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为什么LED灯比白炽灯更省电

LEDs produce light through electroluminescence, where electrons release photons directly in a semiconductor.
White incandescent bulbs heat a tungsten filament until it glows, wasting over ninety percent as heat.
Because LEDs avoid thermal radiation, they convert nearly ninety percent of energy into visible light.
A typical LED uses only eight watts to match the brightness of a sixty-watt incandescent bulb.
Their solid-state design lacks fragile filaments, making them far more durable and efficient.
Heat sinks manage the small amount of waste heat LEDs do generate near the chip.
Unlike older bulbs, LEDs dim smoothly without changing color temperature or efficiency.
They last twenty-five times longer, reducing both energy use and replacement frequency.
Even in cold environments, LEDs start instantly and maintain full output without power surges.
This fundamental physics difference explains why cities worldwide are switching streetlights to LED arrays.

听 → 读 → 学表达 → 懂 → 今天会说这一句 → 跟读录音 → 自己说一句。

Unlike older bulbs, LEDs dim smoothly without changing color temperature or efficiency. 与传统灯泡不同，LED调光时色温与效率均保持稳定。
They last twenty-five times longer, reducing both energy use and replacement frequency. LED寿命长达白炽灯的25倍，显著降低能耗和更换频率。
LEDs produce light through electroluminescence, where electrons release photons directly in a semiconductor. LED通过电致发光产生光，电子在半导体中直接释放光子。

这篇中文题目最接近哪一句？为什么LED灯比白炽灯更省电一次学校运动会的通知一份超市购物清单

课文第一句的意思更接近？ LED通过电致发光产生光，电子在半导体中直接释放光子。今天学校放假了。请把窗户打开。

这一课主要在讲什么？（看英文标题） Why LEDs Use Less Power Than Incandescent Bulbs How to cook noodles A maths worksheet

Unlike older bulbs, LEDs dim smoothly without changing color temperature or efficiency.

Unlike older bulbs, LEDs dim smoothly without changing color temperature or efficiency.

第一版：录下来、回听、再听标准音。系统打分以后再加。

用今天的表达，自己说一句。

例子：Unlike older bulbs, LEDs dim smoothly without changing color temperature or efficiency.