What's the best way to create a colour spectrum?

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Offline thedoc

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What's the best way to create a colour spectrum?
« on: 29/07/2016 22:23:02 »
Graham Cole asked the Naked Scientists:
   My grandson (Luke age 13) and I have being trying to create a colour spectrum but have met with only very limited success. We have prisms, multi led torches , single bulb torches. Black paper with slits and pinprick holes, dark room,  lit room, but cannot produce a satisfactory image. Can you suggest where we are going wrong or recommend a primer for this aspect of physics please?

Pleased excuse this naive query,

Thank you.

Graham and Luke
What do you think?
« Last Edit: 29/07/2016 22:23:02 by _system »

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Offline Colin2B

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Re: What's the best way to create a colour spectrum?
« Reply #1 on: 29/07/2016 22:36:18 »
Have you used sunlight and a prism?
Led and tungsten bulbs have a restricted spectrum.
and the misguided shall lead the gullible,
the feebleminded have inherited the earth.

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Offline evan_au

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Re: What's the best way to create a colour spectrum?
« Reply #2 on: 30/07/2016 05:12:33 »
A beam of sunlight in a dark room should reveal a good rainbow - after you adjust the prism to get a good angle.

There are also those "novelty glasses" that surround lights by rainbow streaks.
They use a diffraction grating to spread the light into a spectrum.
Just be careful not to look at the Sun with these, as the Sun is very bright.

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Offline RD

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Offline CaptMoldman

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Re: What's the best way to create a colour spectrum?
« Reply #4 on: 02/08/2016 17:15:47 »
I don't think this is a naive query at all (but maybe I'm the most naive one here!) I've never set out to create a color spectrum myself but I didn't notice one created by chance while laying on my couch after work. The sunlight was actually hitting a crystal piece from my wife's chandelier and creating a brilliant rainbow across our ceiling. I suspect the scientists above have already provided you all you need to get your spectrum, but on the off chance you have a shard of quartz crystal or something to that effect just lying around, you could hold it up to the sunlight and see if it acts as a prism the way the crystals in the chandelier did for me.

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Offline Atomic-S

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Re: What's the best way to create a colour spectrum?
« Reply #5 on: 03/08/2016 05:42:18 »
It seems to me that I got a very good spectrum out of sunlight hitting a glass of water at about 45 degrees to the water surface and refracting it into the sink about 30 cm below. That would constitute a 45 -- 45 -- 90 degree prism with the sunlight traveling parallel to the hypotenuse.  However, my figures could be a bit off because it was quite some time ago and I do not definitely recall the details precisely. so the stated angles could be a little off. What I do know is that it split the colors quite effectively.