(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

Calculate the minimum thickness of a layer of manesium flouride(n=1.38) on flint glass (n=1.66) in a lens system, if light wavelength 5.50x10^2 nm in air undergoes destructive interference.

Given:

n1=1.38

n2=1.66

λ1=5.5*10^2 nm

2. Relevant equations

Δx=L(λ/2t)

n2/n1 = λ1/λ2

3. The attempt at a solution

Destructive interference is at λ/4, 3λ/4, 5λ/4 ....

So the λ in flint flass is λ2=(n1*λ)/n2

= 4.57 * 10^-7

Therefore the shortest thicknss should be λ/4

4.57*10^-7/4

1.14*10^-7

The answer however is wrong the answer is suppose to be 199 nm.

Can someone please help! Thanku

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# Homework Help: Calculate Interference in thin films

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