Thin Film Interference and wavelength

In summary, a light of wavelength 550 nm in air is normally incident on a glass plate with a refractive index of 1.5 and a thickness of 1.1 x 10^-5 m. The problem asks for the thickness of the glass in terms of wavelength in glass, the number of reflected waves experiencing a 180 degree phase shift, and whether the reflected waves will interfere constructively or destructively. The correct answer may depend on the specific wording of the problem.
  • #1
Aoiumi
23
0

Homework Statement


Light of wavelength 550 nm in air is normally incident on a glass plate (n=1.5) whose thickness is 1.1 X 10^-5 m. (a) What is the thickness of the glass expressed in terms of the wavelength of light in glass?(b) How many reflected waves will experience the 180 degree phase shift? c) Will the reflected waves interfere constructively or destructively?


Homework Equations



t min = λ / 4n1


The Attempt at a Solution


I'm really not sure where to begin with this one. Here's what I have:

λm = 550 nm / 1.5 =366.6 nm ~ 360 nm

1.1 x 10 ^ -5 = 360 / 1.5

This doesn't make sense. Could someone please point me in the right direction? Thank you!
 
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  • #2
You are right, the wording of the problem doesn't make sense.

ehild
 

What is thin film interference?

Thin film interference is the phenomenon that occurs when light waves reflect off the top and bottom surfaces of a thin film, causing interference and resulting in a particular color or pattern.

What is the difference between constructive and destructive interference?

Constructive interference occurs when the reflected light waves reinforce each other, resulting in bright or intense colors. Destructive interference occurs when the reflected light waves cancel each other out, resulting in darker or duller colors.

How does the thickness of a film affect interference patterns?

The thickness of a film determines the path difference between the reflected light waves, which in turn affects the interference pattern. Thicker films result in a larger path difference and more distinct interference patterns, while thinner films may not exhibit noticeable interference.

What is the role of wavelength in thin film interference?

The wavelength of light determines the color of the interference pattern. Longer wavelengths, such as red light, result in larger path differences and therefore more distinct patterns, while shorter wavelengths, such as blue light, result in smaller path differences and less distinct patterns.

What are some real-life applications of thin film interference?

Thin film interference is used in various technologies, such as anti-reflective coatings for glasses and camera lenses, optical filters, and in the production of colorful iridescent films on certain objects. It is also used in scientific research to study the properties of thin films and to measure the thickness of materials.

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