Wave Phenomena

Introduction to Interference

What happens when two or more waves overlap

Show Me The Physics waves lesson

 

 

 

Video Instruction

showmethephysics.com

 

 

 

This movie is part of the collection: Prelinger Archives

Producer: Coronet Instructional Films
Sponsor: N/A  Audio/Visual: Sd, B&W
Keywords: Perception: Sound

Creative Commons license: Public Domain

Sound__Wavelength.mp4

 

 

 

 

 

E.  Wave Front – locus of adjacent points on a wave which are in phase

 

Top View

Ex) Distance between arrows = .90 cm

 

Wavelength of  wave?

 

 

 

 

 

 

λ = .30 cm

 

 

 

III. Periodic Wave Phenomena

 

Wave Interference - St. Mary's Physics 2011 

St. Mary's Physics YouTube Channel 

 

 

 

 

Beats
When Sounds Overlap
(Video)

- Bob Barrett

 

 

 

Interference – effect produced by two waves passing simultaneously through a region

 

 

1. Superposition – when waves overlap, the resultant displacement is the algebraic sum of the individual displacements of each wave

 

 

Superposition

Monterey Institute

 

 

a) Constructive Interference

Transverse and Longitudinal Waves
Emily Wee

Wave Interference
Show Me The Physics

Student YouTube Channel

St. Mary's Physics 2011 

Spring Wave - "Show me the Physics" 
 
Show Me The Physics
Students YouTube Channel

 

 

1)

 

 

 

 

 

 

2)

Amplitude?

 

 

2A

 

 

 

3)

 

 

 

Waves reemerge as separate waves

 

 

b) Destructive Interference

 

[ Flash ]

 

1.

 

 

 

2.

At moment of overlap, amplitudes cancel
(for a moment)

 

 

 

 

 

3.

Waves reemerge as separate waves

 

 

 

 

 

 

[ Flash ]

 

 

"As the two waves below pass through each other, the medium at

point P will ..."

(1) vibrate up and down

(2) vibrate left and right

(3) vibrate into and out of the page

(4) remain stationary

June 2004

 

 

 

 

 

(4) remain stationary

 

 

 

 

 

What will the amplitude

of the resultant wave be

when wave A and B

meet at point X?

Jan. 2004

 

 

 

 

 

+1

 

 

 

 

 

What is the amplitude

of the wave produced

when these waves

overlap?

June 2009

 

 

 

15 cm

 

 

Ranking Task

The diagram below shows two waves traveling in the same medium. Points A, B, C, and D are located along the rest position of the medium. The waves interfere to produce a resultant wave.

Rank the magnitude of the displacement from the equilibrium position from greatest to least. Ties Are Possible.

 

 

 

 

 

Application - Noise Cancelling Headphones

 

A noise wave plus its inverted anti-noise wave adds to a flat line

🎧 Podcast · 1½ min

How Anti-Noise Creates the Illusion of Silence

More episodes →

 

 

 

 

 

Interference -  1 | 2 | 3 |

(Right Click, Save As, Open)

Doane College

 

 

 

- Paul Hewitt

 

Constructive Interference

[ HTML5 ]

(Jason P. - 2005)

Constructive Interference II

[ HTML5 ]

(R. Meija - 2005)

Destructive Interference

[ HTML5 ]

(Jason P. - 2005)

 

 

 
Superposition of sound waves: two in-phase waves add up to a wave twice as tall (louder), while a jet-engine noise wave plus its inverted anti-noise wave add up to a flat line (silence) NYSSLS Reading Passage icon

NYSSLS Reading Passage · Waves

Sound Waves & Active Noise Cancellation

Open Reading Passage →

Check Your Understanding

5 quick questions — pick an answer to see if you’re right.

1. A 3 cm pulse and a 5 cm pulse, both upright, meet in a spring. What is the amplitude when they completely overlap?

2. A +4 cm pulse meets an identical −4 cm pulse (on the opposite side). At the moment they completely overlap, the medium at that point is…

3. After two pulses pass through each other, they…

4. Noise-cancelling headphones play an “anti-noise” wave. Compared with the incoming noise, it has…

5. According to the principle of superposition, when waves overlap the resultant displacement is…

Symmetrical Interference →