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Home Minds On Vibrations and Waves Mission WM6 Interference of Waves Help Help 7

Mission WM6 Interference of Waves

The Question

The diagram below shows two sine waves present in the same medium; several points along the medium are labeled with letters. The displacement of the resultant wave pattern at point B would be approximately ___ units.

Physics Rules

Principle of Superposition:
When two waves traveling along the same medium interfere with each other, the medium takes on a new size and shape which is the result of the combination of the size and shape of the two interfering waves. The resulting displacement of the medium at any given location can be determined by adding the vector displacements caused by each individual wave at that location. When adding the displacements of the individual waves, their direction of displacement must be considered in addition to the amount of displacement.

Game Plan

To be successful at this question, you will need a good strategy and some attention to detail. To begin, locate the letter in question. Then look along the vertical line at that location and determine the amount of displacement of each individual wave from the resting location (bold line). Take notice of the amount the medium is displaced from rest at that location and the direction it is displaced - up or down. Then add the two individual displacements (calling a down displacement a negative value). The sum is the resulting displacement of the medium at that location.

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