Skip to Content Go to sign in Skip to Primary Navigation Skip to Secondary Navigation Skip to Page Navigation Skip to Header Navigation Skip to Footer Navigation Read more about accessability options and our navigation

Physics Classroom is making strides to make our site accessible to everyone. Our site contains 6 navigation areas. The Primary, Secondary, and Page Level navigations have a screen reader version of their nav structure that allows using the left and right keys to navigate sibling navigation items, and up or down keys to navigate parent or child navigation items. The others can be navigated using tabs. The Primary Navigation handles the first 2 levels of site pages. The Secondary (which is not always available) handles the 3rd and 4th level of structure. The Page level navigation allows you to navigate the current page's headings quickly. The Header Navigation contains the Light/Dark Mode toggle, Search, Notifications and account login. The Breadcrumb Navigation contains the breadcrumb of the current page. If the current page has a breadcrumb, you can get to it by skipping to the content and tabbing in reverse (shift plus tab). The Footer Navigation contains links such as Privacy, Contact, about and terms. Some resources contain an Audio Player that can be activated by holding down the T key for 3 seconds, and then using K to pause and resume. While not every area of Physics Classroom is usable purely from keyboard and screen reader, we are committed to continue work on making this possible. If you have questions or need additional help, please use this link to contact us.

Return to screen reader navigation
Home Concept Builders Vibrations and Waves Wave Interference Help Help 1

Wave Interference - Questions 1 Help

When two or more waves meet up while traveling through the same medium, they undergo interference. The interference that occurs can be classified as either constructive or destructive interference.

There are two similar versions of this question. Here is one of the versions:

Version 1:
Wave 1 (in Red) and Wave 2 (in Blue) are moving through the same medium and undergoing interference. They have different wavelengths, frequencies, and amplitudes. For the five labeled points, categorize each as being locations where either constructive or descructive interference occurs.
 
Constructive interference occurs at locations: A B C D E (Circle)
Denstructive interference occurs at locations: A B C D E (Circle)

When two waves travel along the same medium, each wave exerts its own individual effect upon the medium. That is to say that each pulse either pulls upward or pulls downward upon the medium by a given amount. But the medium can have only one response. It can't show both waves; it must show the combined effect of both waves. And this combined effect is easily determined by simply adding the two individual effects. This is known as the Principle of Superposition.

To determine the effect at each location, simply add the displacement of both waves at that location. That is, measure (or count) upward (or downward) to the red wave to determine the displacement of the medium that results from the red wave. Repeat this measurement (or count) for the blue wave. Add the two numbers together and the result is the combined displacement at that location. Note that one or both of the numbers that you are adding together could be negative (for downward).

Try this link to The Physics Classroom Tutorial for more help with understanding wave interference:

Interference of Waves

Concept Builder Teacher Notes Directions