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
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:
 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?
 What should be the total number of photons detected as a function of the distance between the two slits?
 Where is the maximum ? In the middle between the two slits ?
 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.
 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.
The program consists of 6 parts, each performing 1 experiment.

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:
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xxx xxx
xx xx
xxx xxx
xxxx xxxx

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.

Part 6 performs a one slit experiment.
Part 6 consists consists of 3 parts.
Suggestions for improvement of this paragraph are appreciated.
Feedback
28/10/96 The program worked nicely.
Last modified: 29 October 1996
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