This lesson explains how waves combine when they meet and how their combined disturbances create interference.
When two or more waves reach the same point, their disturbances combine. This is called superposition. For disturbances along the same line, the resulting displacement is the sum of the individual displacements at that point.
The disturbances can reinforce one another or partly or completely cancel. This is why a complicated-looking wave can result from the addition of simpler waves.
All flashcards
Superposition
When waves meet, their disturbances combine; for waves along the same line, their displacements add.
Constructive interference
Interference in which disturbances reinforce one another; identical in-phase waves produce twice the individual amplitude.
Destructive interference
Interference in which disturbances oppose one another; identical waves exactly out of phase cancel completely.
Standing wave
A stationary pattern formed when waves traveling in opposite directions superimpose; its component waves continue to travel.
Beats
Pulses of changing loudness caused by interference between similar, unequal frequencies. Their frequency is fB=∣f1−f2∣.
Quiz questions
How can two waves form a standing wave?Answer: Equal-frequency, equal-amplitude waves traveling in opposite directions superimpose.
What is the fundamental wavelength of a string fixed at both ends, if its length is L?Answer: 2L
For a string fixed at both ends, how does the frequency of the nth harmonic relate to the fundamental frequency f1?Answer: fn=nf1
In a structure driven by periodic motion, what condition can produce resonance and large vibrations?Answer: The driving frequency matches a natural frequency of the structure.
Two sound waves have frequencies f1 and f2. What is their beat frequency?Answer: ∣f1−f2∣
Based on College Physics 2e by Paul Peter Urone, Roger Hinrichs (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.