Another Physics Problem

QL · 发表于 2005-10-1 19:59:56

我们知道，在凸透镜的一侧放一烧红的铁块，那么热辐射在另一侧会聚焦，焦点的温度会比周围要高。如果把烧红的铁块换为冰块，那么在另一侧焦点的温度是不是会比周围低？

QFT · 发表于 2005-10-1 22:10:47

the temperature of the focus is always higher.

ob · 发表于 2005-10-2 11:42:50

Cause the 凸透镜is focus the red light and infrared light on the other side. Ice does not emit infrared or red light.

husonghu · 发表于 2005-10-2 11:55:06

冰块无热辐射，That's the point.

QL · 发表于 2005-10-2 16:25:09

That is exactly the point. But the answer is yes.

A hint: under ordinary in-door condition on earth, there is radiation evenly from every direction...

QFT · 发表于 2005-10-2 21:08:36

Will a piece of iron in contact with ice radiate light?

QL · 发表于 2005-10-2 22:49:11

I'm no physics major, my understanding is that every object with temperature above absolute zero will radiates light, but the intensity varies according to temperature.

QFT · 发表于 2005-10-3 01:19:58

yes, you are right. the intensity is proportional to T^4, where T is the temperature relative to absolute zero. The frequency of the emitted light also depends on temperature. The higher the temperature, the higher frequency of the light.

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Another Physics Problem

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I think the answer is no.

Agree,.........

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