Diffraction Patterns

[Sonia Aronson 1B]

One of the post-module questions is:
19. What causes a diffraction pattern?

A. Slit in the barrier works as a filter to create a diffraction pattern.

B. Different wavelengths which the light composes.

C. Different intensities of a light wave

D. Two or more waves interacting constructively and destructively.
Could someone explain the answer and what diffraction is?

[octaviahuang1f]

I believe the answer is D.
From Dr. Lavelle's lecture last week, diffraction pattern is
a combination of destructive and constructive waves that leads to specific patterns based on what is causing the diffraction.
Constructive interference is "in phase", meaning the waves' peaks and troughs coincide and the resulting amplitude would be their sum.
Destructive inteference is "out of phase", meaning one of their peaks coincide with the other wave's troughs, and thus decrease the amplitude of the resulting wave.

[vivianndo_1L]

Here's a really good Crash Course video that helps conceptualize diffraction and its significance in Quantum Theory:

https://youtu.be/IRBfpBPELmE

It'll help visualize the constructive and destructive waves as well.

[Raquel Floyd 1K]

While reviewing, I found the whole first three sections on khan academy "quantum physics" very helpful. Here is a video that explains the experiment that shows defraction patterns https://youtu.be/iTRxuBxttj8