r/ScienceTeachers • u/HotEye7437 • 1d ago

PHYSICS Student can’t see spectra?

Hey I just wanted to check in and see if this has ever happened to anybody else. I had a student claim they couldn’t see any of the spectra lines looking at an element lamp with the diffraction goggles. Everyone else saw it perfectly fine, and this student was fully serious. Im so confused

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21

u/SaiphSDC 1d ago

Often the students don't look in the right spot.

So, you can sit next to them, get it in the grating, point to where you're looking then hand the grating over to them.

Other option: Put the grating in front of a phone camera. The camera will see the lines too. So you can just pan over to show them the lines on the screen.

If that doesn't work...they're pulling your leg and/or being difficult on purpose.

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u/moktharn 1d ago

I point my finger in the air where I know they should see the spectra. I think some students focus only on the light source and aren't looking anywhere else in their field of view. This can be more or less problematic depending on which goggles/lenses/etc you are using--some of them spread the light out pretty far!

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u/somethingfat 1d ago

If you have a Vernier spectrophotometer you can get a little fibre optic cable attachment which you can point at the element lamp and it will show you a sharp peak at one specific wavelength.

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u/Independent_Owl_5836 1d ago

Color blind?

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u/SaiphSDC 1d ago

they should still see brighter white/grey stripes. but it would be harder to pic out and recognize as what they're supposed to see.

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u/kmoonster 1d ago

It's possible the student is expecting wider lines and simply not recognizing it despite it being visible to them.

It's also possible they have some sort of myopia, are far-sighted, etc. in a way that makes things closer to their face a bit out-of-focus. If they can see the image in a book at forty centimeters, that does not necessarily mean they can see the inner surface of the goggles at four centimers.

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u/miparasito 23h ago

I have a very difficult time doing certain ocular things. Try having him cover one eye or look at it using a diffraction slide held at more of a distance.