We are going to use this week’s lab assignment as an opportunity to learn about
We are going to use this week’s lab assignment as an opportunity to learn about other type of diffraction interference pattern.
Open up the above simulation and switch to the “Diffraction” tab.
Select the square hole setting for the screen on the left.
Reduce “width” to its minimum value and set “height” to its maximum value.
Press the big red button on the laser (upper left corner) to turn on the laser.
Notice how the top shows you that the laser is going through the screen with a hole in it, then the interference pattern is shown on the screen all the way to the right.Question 1: This interference pattern should look familiar. How is it similar to single slit diffraction? How is it different?
Gradually reduce “height” to 0.1 mm.Question 2: How did this change the interference pattern?
Gradually increase “width” to 0.1mm.Question 3: The new interference pattern should have some symmetry to it. What is the source/cause of that symmetry? How would you describe this interference pattern in comparison to the single slit interference we are used to?
Switch to the circular hole.Question 4: Describe the new interference pattern.
Decrease the diameter to its minimum value.Question 5: How does making a hole smaller affect the diffraction pattern?
Switch to the circle and square combination hole.
Play around with the size of the square, then reset it to 0.05 mm.
Play around with the size of the circle, then reset it to 0.05 mm.Question 6: There are several parts to this interference pattern. What part of the interference pattern can be explained by the size of the square? What part can be explained by the size of the circle?
Question 7: What part of the interference pattern cannot be attributed to the size of the circle or square? What might be the cause of that part of the pattern?
Select the 4×4 grid of circular holes.
Play around with all three sliders for this hole.Question 8: How does each slider affect the diffraction pattern?
Question 9: If you want to create a diffraction pattern that doesn’t appear to repeat, what setting on the sliders would you pick?
Take a look at the following image from the James Webb Space Telescope: image credit NASALinks to an external site.
You hopefully will notice that the stars all have a bunch of lines radiating out of them.
Next, take a look at this picture of the actually space telescope: image credit NASA
Question 10: After observing the lines radiating out of the stars, as well as the structure of the telescope, what might be the cause of the interference pattern observed in the space image above? Take your best guess.
See an explanation for this phenomenon here: BBC Science FocusLinks to an external site.