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Wave Interference. Physics Ch 12. Sec. 4. - When two waves come together they can occupy the same space Superposition – multiple waves occupying the same space Mechanical and electromagnetic waves can do this. Wave Interactions. Interferance –
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Wave Interference Physics Ch 12. Sec. 4
- When two waves come together they can occupy the same space Superposition – multiple waves occupying the same space • Mechanical and electromagnetic waves can do this
Wave Interactions Interferance – combination of 2 or more waves usually produces one wave (bigger if in phase) (smaller if out of phase)
Types of Interference 1. Constructive Interference – individual displacements on the same side of equilibrium add together to form a resultant wave (in phase) - If two pulses move toward each other and are on the same side of equilibrium their amplitudes add together to form a larger wave
Wave Interactions Constructive interference – when waves combine to create a bigger wave sum of the amplitudes of the waves
- They move through and past each other - Superposition principle – method of summing the waves to get a resultant wave
Wave Interactions 2. Destructive interference – when waves combine to form a smaller or no wave some may completely cancel out difference between the amplitudes of the waves
2. Destructive interference – individual displacements on opposite sides of equilibrium are added together to form a resultant wave (out of phase)
Reflection - When a wave strikes a boundary it bounces (reflects) off of that boundary
1. Free boundary – pulse is reflected identical to the pulse • The rope / spring / medium is free to move up and down at the boundary
2. Fixed boundary – pulse is reflected but is inverted The rope / spring / medium is tightly secured at the boundary and is not free to move up or down
Standing waves • - Wave pattern that appears to stand still from waves traveling in opposite directions • Waves at same frequency • Creates spots of zero displacement
- Node – point on a wave that stands still due to total destructive interference always occurring • Antinode – point on a standing wave halfway between two nodes (point of largest displacement) *Only certain frequencies produce standing waves
Wave Behaviors A. Refraction - bending of waves as they pass from one medium to another
Wave Behaviors B. Diffraction – bending of waves around an edge
Wave Interactions - Wave speed depends on the medium ex. Sound moves fastest through solids moves moderately fast through liquids moves slowest through air/gases (340 m/s) - due to movement of molecules in the medium
Wave Interactions Light travels at a constant speed 3x 108 m/s = 300,000,000 m/s (186,000 miles/sec.) - symbolized as “c”