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

Double slit experiment: effect of changing wavelength

  • Thread starter coconut62
  • Start date
  • #1
161
1

Homework Statement



The question is regarding Young's double slit experiment.

"Describe the effect, if any, on the separation and on the maximum brightness of the fringes when the following changes are made.
...
...
2) The wavelength λ is increased to 1.5λ, keeping a and D constant.

Separation:
Maximum brightness:

Homework Equations



λ=ax/D

The Attempt at a Solution



My answer:

Separation: Increases by 1.5 times
Maximum brightness: Same (Wrong, answer: less bright)

Why would the change in wavelength alter the brightness of the fringes?
 

Answers and Replies

  • #2
Simon Bridge
Science Advisor
Homework Helper
17,848
1,645
Sensitivity of the eye to different wavelengths perhaps?
How is brightness defined here?

For a longer wavelength, the brightness of the fringes would probably fall off more with the order of the fringe ... since the light has further to go to reach the screen. But I'd have said the central fringe would have the same brightness for all wavelengths affected - evidence: white light interference: the central fringe is white.
 
  • Like
Likes 1 person

Related Threads on Double slit experiment: effect of changing wavelength

Replies
1
Views
2K
Replies
0
Views
3K
Replies
2
Views
1K
Replies
8
Views
12K
Replies
1
Views
249
Replies
4
Views
144
Replies
5
Views
4K
Replies
3
Views
10K
Top