Destructive interference and fringes

In summary, a person is seeking help with finding the distance between the 2nd and 3rd dark fringes on a screen. They are using a formula with variables for the wavelength, distance between slits, and distance between grating and screen. The formula is not working and they are asking for assistance. They later realize their mistake was a unit conversion error. They also mention having another question about interference in a film.
  • #1
Joza
139
0
I am looking for the distance between the 2nd and 3rd DARK fringes on a screen.

Monochromatic, coherent light is shone through 2 slits a distance d apart.

Wavelength is L. Distance between grating and screen is R.

The formula I am using is: [(R(5/2)L)/d - (R(3/2)L)/d]

I am using 5/2 and 3/2 since these should be the number of wavelengths for destructive interference for the 3rd and 2nd fringes respectively.

The formula doesn't seem to be working though. Where have I gone wrong?
 
Physics news on Phys.org
  • #2
BUMP!:approve:

Come on guys. Any help? I really need to get this sorted today.
 
  • #3
Your formula looks OK to me. Why do you think its wrong?
 
  • #4
I feel like an idiot.


Ah it was a classic unit conversion error!:blushing:


Thanks tho!
 
  • #5
D'oh! (Been there, done that.)
 
  • #6
Could you help me with my final part so?
 
  • #7
Joza said:
Could you help me with my final part so?
Final part of what?
 
  • #8
I have 2 questions relating to light. This is one. I have posted the other. It is do with interference in a film.

Please excuse the posts in the thread. The first one relates to the question.
 

1. What is destructive interference?

Destructive interference is a phenomenon where two waves with opposite amplitudes meet and cancel each other out, resulting in a decrease in the overall amplitude of the wave. This can occur when two waves of equal frequency and amplitude are out of phase with each other.

2. How does destructive interference create fringes?

Destructive interference can create fringes when it occurs in a pattern, such as in the double-slit experiment. The interference pattern is created by the varying degrees of destructive interference at different points where the waves overlap, resulting in areas of dark and light fringes.

3. What factors affect the intensity of fringes in destructive interference?

The intensity of fringes in destructive interference can be affected by the wavelength and amplitude of the waves, as well as the distance between the sources and the observer. Additionally, the phase difference between the waves and the medium through which they are traveling can also impact the intensity of fringes.

4. How do fringes in destructive interference differ from those in constructive interference?

In destructive interference, the waves have opposite amplitudes and cancel each other out, resulting in dark fringes. In contrast, constructive interference occurs when waves with the same amplitude and frequency are in phase and combine to create a larger amplitude, resulting in bright fringes.

5. What are some real-life examples of destructive interference and fringes?

Destructive interference and fringes can be observed in many natural and man-made phenomena, such as ripples on the surface of water, thin film interference in soap bubbles, and diffraction patterns in x-ray crystallography. They can also be seen in audio and radio signals, as well as in noise-cancelling technology.

Similar threads

Second bright fringe in Young's Experiment
    • Introductory Physics Homework Help
Replies
3
Views
537
Number of bright fringes given by diffraction grating on a screen
    • Introductory Physics Homework Help
Replies
5
Views
1K
Single Slit Interference Pattern: Increased Distance
    • Introductory Physics Homework Help
Replies
1
Views
2K
Constructive, destructive interference help please
    • Introductory Physics Homework Help
Replies
10
Views
954
Thomas Young's double slit experiment
    • Introductory Physics Homework Help
Replies
6
Views
3K
With the info given, what are 3 ways to calculate wavelength?
    • Introductory Physics Homework Help
Replies
1
Views
813
Double Slit Wave Interference - what is m?
    • Introductory Physics Homework Help
Replies
1
Views
1K
Predicting Changes in Interference Patterns using Laser Interference Equations
    • Introductory Physics Homework Help
Replies
3
Views
1K
Single lens creating a diffraction pattern?
    • Introductory Physics Homework Help
Replies
6
Views
1K
Correct statement about coherent sources and interference
    • Introductory Physics Homework Help
Replies
18
Views
1K

Hot Threads

Recent Insights

Back
Top