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Thread: Prisms question

  1. #1
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    Big Smile Prisms question

    Hi can anyone help me answer this question

    Construct a triple tangent scale for use at 2.5 metres on which you could read thepower of an unknown prism in prism dioptres, degrees of deviation and degreesof apical angle (assume a refractive index of 1.523)

  2. #2
    What's up? drk's Avatar
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    I think the gist of it is you have to do a science project.

    Like, get a piece of cardboard and put it 2.5M from a prism sitting on a table (maybe base down).

    Shine a beam of light through it. Like a cool laser! But you'd need "collimated light" I think, so get out the optical bench.

    Measure the deviation from dead center.

    Then use math to calculate prism diopters and degrees of deviation, and then plug and chug into the formula that includes the apical angle (which I only vaguely remember).

    Good luck!

    Oh, what's a triple tangent scale? I can see how one would use trigonometry, here, but they're looking for you to devise a scale to read on the cardboard that you could maybe answer all three questions (apical angle, degrees, p.d.) for any prism you'd put in there.

  3. #3
    My Brain Hurts jpways's Avatar
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    When I googling for a tangent scale I came across this https://www.speedwaydelhi.com/produc...ent-scale.html
    Which could be used to measure prism, but I doubt that's called a triple tangent scale as it's only in 2 axes, maybe the 3rd axis is an object that measures/controls distance since you would need a way to convert the distance to 1m to properly measure prism.
    Last edited by jpways; 03-13-2018 at 01:35 PM.

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