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Vibrations and Waves. Wave Interactions. Interference. Interference – the combination of two or more waves that exist in the same place at the same time Waves in the same place combine to produce a single wave Superposition. Interference.
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Vibrations and Waves Wave Interactions
Interference • Interference – the combination of two or more waves that exist in the same place at the same time • Waves in the same place combine to produce a single wave • Superposition
Interference • Constructive interference – displacement in the same direction • Interference in which individual displacements on the same side of the equilibrium position are added together to form the resultant wave • Crests of waves overlap or troughs of waves overlap • Amplitudes are added
Interference • Destructive interference – displacement in the opposite direction • Interference in which individual displacements on opposite sides of the equilibrium position are added to form the resultant wave • Crest of one wave meets the trough of another wave • Essentially, amplitudes are subtracted
Interference • Interference in light waves create colors • Light separates into different colors • Rainbow effects • Interference in sound waves create beats • Constructive interference produces loud sounds • Destructive interference produces soft sounds • Patterns of constructive and destructive interference alternate loud and soft sounds, producing beats
Reflection • Reflection – the bouncing back of a wave as it meets a surface or boundary • At a moveable boundary, the reflected wave looks just like the original wave • At a non-moveable boundary, the reflected wave is turned upside down
Diffraction • Diffraction – the bending of a wave as it passes an edge or an opening • Waves spread out to fill space • Allows us to hear sounds through doors
Refraction • Refraction – the bending of waves as they pass from one medium to another • All waves are refracted when they change media • Refraction explains why spoons look broken when part of them is in air and part in water
Standing Waves • Standing wave – a wave pattern that results when two waves of the same frequency, wavelength, and amplitude travel in opposite directions and interfere • Standing waves do not move through the medium • Standing waves cause the medium to vibrate in a loop or in a series of loops
Standing Waves • Nodes – a point in a standing wave that always undergoes complete destructive interference and therefore is stationary • areas of no vibration • Antinodes – a point in a standing wave halfway between two nodes, at which the largest amplitude occurs • areas of maximum vibration • Standing waves occur at specific frequencies