Lesson 4.4 - Thin Films
VIDEO LESSON (20:38 min)
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Since the frequency of light (colour) doesn't change as it goes into a new medium the wavelength must also go down. This can be calculated by:
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THIN FILMS
RECALL: INDEX OF REFRACTION
Recall that a medium slows the speed of light by a factor referred to as the index of refraction.
Since the frequency of light (colour) doesn't change as it goes into a new medium the wavelength must also go down. This can be calculated by:
When light reflects off of a slower (denser) medium (\( n_1 < n_2 \), air to water, air to glass) the waves invert their phase (flip). If \(n_1 > n_2\) there is no flip.
For a very thin layer of material (\( t << \lambda \)) this will cause destructive interference.
EXAMPLE
最后修改: 2025年06月23日 星期一 22:59