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Chapter 11. Section 4 wave interactions. Objectives. Apply the superposition principle. Differentiate between constructive and destructive interference. Predict when a reflected wave will be inverted. Predict whether specific traveling waves will produce a standing wave.
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Chapter 11 Section 4 wave interactions
Objectives • Apply the superposition principle. • Differentiate between constructive and destructive interference. • Predict when a reflected wave will be inverted. • Predict whether specific traveling waves will produce a standing wave. • Identify nodes and antinodes of a stand
Wave Interference • When two bumper boats collide , each bounces back in another direction. • Two different material objects can never occupy the same space at the same time. • So they are force to change direction.
Waves interference • When two waves come together , they do not bounce back as bumper boats do. • If you listen carefully at a concert, you can distinguish the sound of different instruments. • For example trumpets sound different from flutes. • The sound waves are unaffected by the other waves that are passing through the same space at the same time . • Because mechanical waves are not matter but rather are displacements of matter, two waves can occupy the same space at the same time. • The combination of two overlapping waves is called superposition.
Types of waves interference • Inconstructive interference, is a superposition of two or more waves in which individual displacements on the same side of the equilibrium position are added together to form the resultant wave.
Types of wave interference • In destructive interference, individual displacements on opposite sides of the equilibrium position are added together to form the resultant wave.
Complete Destructive interference • That is when the resultant displacement at each point of the string is zero, so the two pulses cancel one another.
Reflection • What happens to the motion of a wave when it reaches a boundary? • At a free boundary, waves are reflected. • At a fixed boundary, waves are reflectedand inverted.
Standing waves • A standing wave is a wave pattern that results when two waves of the same frequency, wavelength, and amplitude travel in opposite directions and interfere. • Standing waves have nodes and antinodes. • A node is a point in a standing wave that maintains zero displacement. • An antinode is a point in a standing wave, halfway between two nodes, at which the largest displacement occurs.
Standing waves • Only certain wavelengths produce standing wave patterns. • The ends of the string must be nodes because these points cannot vibrate. • A standing wave can be produced for any wavelength that allows both ends to be nodes. • In the diagram, possible wavelengths include 2L (b),L (c), and 2/3L (d).
videos • Properties of waves • http://app.discoveryeducation.com/player/view/assetGuid/FA748701-8BD2-4AC8-90D5-ABBED4C8A4E9 • Wave interference video • http://app.discoveryeducation.com/player/view/assetGuid/B920C70B-7C2A-46BC-A9AD-3019D95C98DC • Nature of waves video • http://app.discoveryeducation.com/player/view/assetGuid/0A54BB7F-7C30-45EA-BA06-695A28B9F8CD