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

The table lists the range of wavelengths in vacuum corresponding to a given color. If one looks through a film which has a refractive index of 1.333 and thickness of 340 nm (nanometers), which color will be 100% transmitted through the film?

Table (Color/Wavelength):

- red/780nm-622nm
- orange/622nm-597nm
- yellow/597nm-577nm
- green/577nm-492nm
- blue/492nm-455nm
- violet/455nm-390nm

A) red

B) yellow

C) violet

D) green

E) white

2. Relevant equations

refractive index of air is 1, so n(air)<n(film)>n(air) condition is met. relevant equations will be:

[tex]t(min)=\frac{\lambda}{2*n(film)}[/tex]

where n(film) is the refractive index of the film and t(min) is minimum film thickness

3. The attempt at a solution

I tried this problem, making n(film)=1.333 and t(min)=340 nm, solving for [tex]\lambda[/tex].

I got [tex]\lambda[/tex]=2*n(film)*t(min)=2*1.333*340=906nm

However, this exceeds the wavelength for any of the colors, and the answer should be(C). What did I do wrong?

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# Homework Help: Thin-film interference question

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