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Homework Statement
A film of MgF2 (n = 1.38) having thickness 1.44 x 10-5 cm is used to coat a camera lens.
What are the three longest wavelengths that are intensified in the reflected light? (Enter your answers from smallest to largest.)
Homework Equations
λn = λ/n
n = index of refrection
for constructive interference:
2t = (m + 1/2)λn
2nt = (m + 1/2)λ
destructive interference:
2nt = mλ
The Attempt at a Solution
Honestly have no idea what the question is asking...
not sure how to combine them, not sure how to find 3 biggest wavelengths
not sure if it is constructive interference or not soo
2nt = (m + 1/2)λ
2(1.38m)(0.000000144m) = (0 + 1/2)λ
(2)(1.38m)(0.000000144m) / (1/2) = λ
λ = 795 nano meters (for m = 0)
^^ Yet says it is wrong
All I can think of is to change m to 1, 2, 3 etc but don't think it works.
Suggestions??