How to Determine Minimum Thickness for Dark and Bright Spots in Soap Films?

Thread starter Motox
Start date Jan 7, 2010
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Thin films

AI Thread Summary

To determine the minimum thickness of a soap film that produces dark and bright spots, the relevant equations are 2t = m (wavelength) for dark spots and 2t = (m + 1/2) (wavelength) for bright spots. Given a light wavelength of 580 nm and a soap film refractive index of 1.33, users can calculate the thickness by substituting the values into these equations. For dark spots, the minimum thickness corresponds to integer values of m, while for bright spots, it corresponds to half-integer values. The calculations are straightforward once the equations are applied correctly. The discussion emphasizes the importance of using the correct formulas for accurate results.

Jan 7, 2010

Motox

Homework Statement

Light of wavelength 580 nm strikes a soap film (n=1.33), which is surrounded by air. What is the minimum thickness needed to produce
a) dark spot?
b) bright spot?

Homework Equations

n1/n2=wavelength 2 / wavelength 1

2t = m (wavelength) <-- dark
2t = (m + 1/2) (wavelength) <--- bright

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Jan 8, 2010

ideasrule

Homework Helper

Those equations are right. Just plug in the numbers are you're done.

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