Physics

I was asked to compare my measured focal length to my calculated focal length. My calculated focal length I figured out by using the formula:

1/di + 1/do = 1/f

Would my measured focal length = my di?
I only measured by di and do in the actual experiment.

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asked by Lena
  1. The experimental values I have are:
    f=12
    object location = 2.5f
    object distance from lens = 35 cm
    image distance from lens = 27 cm

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    posted by Lena
  2. The "measured focal length" is the value of f that you compute using the lens formula and your measured values of di and do. In this case, that would be given by
    1/27 + 1/35 = 1/f,
    which leads to f = 15.2 cm

    According to your measurements, the focal length is not 12 cm.

    If you were supposed to have an object location of 2.5 f and the focal length were really 12 cm, the object should have been placed 30 cm from the lens, not 35.

    How did you get the "experimental value" of f = 12 cm? Did they tell you what it is?

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    posted by drwls

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