Confused on Constructive/Destructive Interference

  • Thread starter BuBbLeS01
  • Start date
  • #1
602
0
Confused on Constructive/Destructive Interference!!!

Homework Statement


A film with n=1.6 is deposited on glass. What is the thinnest film that will produce constructive interference in the reflection of light with a wavelength of 575 nm?


Homework Equations





The Attempt at a Solution


I have 2 equations that I can choose from...

Constructive Interference for 0 to 2 refl. phase changes
Destructive Interference for 1 refl. phase changes
2T = m * t/n
t = wavelength

Destructive Interference for 0 to 2 refl. phase changes
Constructive Interference for 1 refl. phase changes
2T = (m + 1/2) * t/n
t = wavelength

How do I know which one to use?

I chose the 2nd one because I assumed there was only 1 phase change.

How do figure out what m =???
 

Answers and Replies

  • #2
458
0
You can't just assume there's only one phase change. You have to see if the reflected beams of light undergo a hard or soft reflection.

As for the value of m, you want it to be as small as possible so that the thickness is as small as possible.
 
  • #3
602
0
whats hard and soft? those terms are not in my book.
 

Related Threads on Confused on Constructive/Destructive Interference

Replies
6
Views
2K
Replies
3
Views
1K
  • Last Post
Replies
5
Views
9K
Replies
5
Views
4K
Replies
17
Views
983
Replies
26
Views
24K
Replies
6
Views
1K
Replies
5
Views
886
Replies
20
Views
1K
Replies
2
Views
2K
Top