Recent content by Grebulous

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    Is the Diffraction Grating's Line Count Accurate?

    This is an intro lab-based question. Homework Statement I took a 650 nm red laser and shined it through a diffraction grating that claimed it had 13500 lines/inch, which comes to 5315 lines/cm in civilized people units. The grating was placed 30 cm away from a piece of paper on the wall...
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    Why do violet and purple look the same?

    First of all, thanks to the folks who answered my question about near-IR light. I've got a question about the other end of the visible spectrum now: why does violet (light with a shorter wavelength than blue) look like purple (a mix of red and blue)? Does our long-wavelength cone have some sort...
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    What is the longest wavelength ever seen by the human eye?

    I've gotten curious about how the human eye's sensitivity to long wavelengths drops off. What's the longest wavelength anybody has ever seen? I know there is nonzero (but very low) sensitivity to 800+ nm light, but does anybody know the extreme long wavelength limit of human vision?
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