本题目来源于试卷: Electric Currents，类别为 IB物理学
[问答题]
Explain why lightbulbs almost always burn l+ydav7/0 xcnfosx0b5p15m i/y(e b t out just as they are turned owz)* -ax2b v0vas shcwm/*w :bn and not after they have been on for some tim b2sas **wvawh )/:x0-mvcwz be.
参考答案:
When
a light bulb is first turned on, it will be cool and the filament will have a
lower resistance than when it is hot.
This lower resistance means that there will be more current through the
bulb while it is cool. This momentary
high current will make the filament quite hot.
If the temperature is too high, the filament will vaporize, and the
current will no longer be able to flow in the bulb.
本题详细解析:
暂无
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