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Thread: what formula should I use?

  1. #1
    OptiBoard Novice
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    what formula should I use?

    Can anyone please help me with this question?

    A lens measure scaled for glass of refractive index 1.654 is placed upon a brass tube and the instrument is rotated until the legs lie at right angles to the axis of the tube. The reading given by the instrument in this position is +10.50, what is the external diameter of the tube in cm?

  2. #2
    ABOM Wes's Avatar
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    65.4/10.5 *2
    Wesley S. Scott, MBA, MIS, ABOM, NCLE-AC, LDO - SC & GA

    “As our circle of knowledge expands, so does the circumference of darkness surrounding it.” -Albert Einstein

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    Master OptiBoarder MakeOptics's Avatar
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    Divide the above respose by 100 to get the measure in centimeters.

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    ABOM Wes's Avatar
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    The formula I provided gives the answer im cm. If you divide it by 100, you will have the answer im meters. The poster asked for a formula that would result in cm, so I provided it.
    Wesley S. Scott, MBA, MIS, ABOM, NCLE-AC, LDO - SC & GA

    “As our circle of knowledge expands, so does the circumference of darkness surrounding it.” -Albert Einstein

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    got it. I misunderstood the question. that's why couldn't get the answer. thanks so much.

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    Glad to see they are still teaching useful applications with the lens clock in optometry school. Normal people would just take a ruler and measure it.

  7. #7
    Dion
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    Quote Originally Posted by PhiTrace View Post
    Divide the above respose by 100 to get the measure in centimeters.
    Yes i totally agreed with you and I'm also using this formula to calculate the diameter. Thanks and i hope in future you also updated us.

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