Program 6: Two Slit Experiment

Introduction and Purpose

The program TWO_SLIT.BAS shows a possible outcome of test 10.
To download a copy select: TWO_SLIT.BAS
To see the listing of the program select: TWO_SLIT.HTM

Functional Description and Operation

The program shows the result of six experiments related to test 10, of: Two slit experiment

Case #1 and case #2 both show when one slit is used. 12400 photons are detected. 12400 is the size of the surface in pixels.
Case #3, case #4 and case #5, each show when two slits are used. The distance between the two slits is different.
Case #6 shows again when one slit is used. The number of photons has to be entered by the user
In case # 3 the distance between the two slits is 1.
In case # 4 the user should enter a value. The preferred value is 0.5.
In case # 5 the user should enter a value. The preferred value is 5
In case # 6 the prefered value for the total number of photons is 12400. In order to get a quick result, try 2000.

The difference between case #1 and case #6 is:

In case #1 only the shape of the curve is shown. The shape should be that of a gauss curve, but it is not.
Case #6 shows the result of an actual test. The curve has the shape of a gauss curve. The mathematics used in getting those results can be improved.


The dispayed 6 outcomes of test 10 are not correct. What the outcomes should be is the purpose of the question.
The possible points of discussion are:
  1. What is the number of photons detected in case #2 assuming that the position of the photon source is not moved, compered to case #1?
  2. What should be the total number of photons detected as a function of the distance between the two slits?
  3. Where is the maximum ? In the middle between the two slits ?
  4. Where are the two slits ? At the first minimum positions ?
    Item 2 and 3 are linked. As indicated in the description of question 10 the position of one slot is fixed and the second one can be different.
  5. What is the # of photons at maximum position ?
    In each test the maximum # of photons in the center is the same, which most probably is not true.

Technical Description

The program consists of 6 parts, each performing 1 experiment.
  1. Part 1 and part 2 perform a one slit experiment.
    The function displayed is 1 + cos(x).
    x goes from 0 to pi.
    The function has the following shape:
                          xxx        xxx
                        xx              xx
                     xxx                  xxx      
                 xxxx                        xxxx                
  2. Part 3,4 and 5 perform a two slit experiment.
    The function is displayed in the subroutine CURVE.
    The function displayed is: {1 + cos(x)} * {1 + cos(x*l/10)} / 2
    l is the size of the slit. x goes from 0 to pi.
  3. Part 6 performs a one slit experiment.
    Part 6 consists consists of 3 parts.
Suggestions for improvement of this paragraph are appreciated.


28/10/96 The program worked nicely.

Last modified: 29 October 1996

Back to my home page Contents of This Document