• Support PF! Buy your school textbooks, materials and every day products Here!

Double Slit Seperation

  • Thread starter TheLegace
  • Start date
  • #1
27
0

Homework Statement



A double-slit with a separation of 2.1 μm is used with white light. Find the angular width of the first
bright fringe between the violet (lviolet = 400 nm) and red (lred = 750 nm) end of the spectrum. (Assume
two significant digits.)


Homework Equations


What exactly are the wavelengths I am using. I am a bit confused.


The Attempt at a Solution


I know the it is the first bright fringe. n=1, d = 2.1um w=?
I am not sure what wavelengths to use.

The formula that I think I could use is

sinӨn=nλ/w

I just don't know where to continue.
 

Answers and Replies

  • #2
Doc Al
Mentor
44,877
1,129
I know the it is the first bright fringe. n=1, d = 2.1um w=?
I am not sure what wavelengths to use.
The wavelengths are given. You'll need them both.
The formula that I think I could use is

sinӨn=nλ/w
In this formula, "w" is the slit separation, which you called "d" above. λ is the wavelength.
 
  • #3
27
0
What exactly is the angular width, isnt it the w variable.

If not then what is d for?

Now I am a bit confused.
 
  • #4
Doc Al
Mentor
44,877
1,129
To avoid confusion, I'd use this formula: sinӨ=nλ/d. This formula gives you the angle made by the nth bright fringe, given the wavelength and slit separation. Find the angle for the first bright fringe formed by each given wavelength. The difference of those angles will be a measure of the "width" of the bright fringe formed by white light.
 

Related Threads for: Double Slit Seperation

Replies
1
Views
5K
  • Last Post
Replies
1
Views
1K
Replies
5
Views
6K
  • Last Post
Replies
1
Views
950
  • Last Post
Replies
5
Views
1K
  • Last Post
Replies
7
Views
1K
  • Last Post
Replies
3
Views
9K
  • Last Post
Replies
2
Views
1K
Top