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

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

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

Reflection

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

Diffraction

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

Refraction

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

Standing Waves

Standing Waves