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10 votes
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Could a transparent frequency-altering material be possible?

Such a thing is possible in principle through the non-linear optical process of half-harmonic generation (and other processes of this class, generally known as photon downconversion). Usually these ...
Riley Scott Jacob's user avatar
5 votes

Could a transparent frequency-altering material be possible?

Yes, there are various materials that take two or more photons of long wavelength and produce one with a shorter wavelength, and vice versa. An example of a "step up" material is KTP, which ...
Maury Markowitz's user avatar
1 vote

Friction and electromagnetic force

I disagree with Bob D that there is no underlying relationship. Instead, what I'd say is that friction is applied electromagnetic forces. Electromagnetic forces dominate interactions between atoms. ...
Cort Ammon's user avatar
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1 vote

What is the thermal expansion equation for a cylinder (plane strain)?

The radial displacement due to temperature change under plane strain is $$\mathrm{d}R = \frac{\alpha R_0}{1 - \nu} \mathrm{d}T$$ where $\nu$ is Poisson's ratio. Plane strain results in higher radial ...
Imogen Fitzgerald's user avatar

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