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Wave Interactions. Reflection. The interaction of a wave with a surface it cannot pass through. Causes the wave to bounce back . Ex: Looking in a mirror – light Ex: Echo – sound Law of reflection – The angle the wave comes in at (incidence) = the angle the wave will be reflected at.
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Reflection • The interaction of a wave with a surface it cannot pass through. • Causes the wave to bounce back. • Ex: Looking in a mirror – light • Ex: Echo – sound • Law of reflection – The angle the wave comes in at (incidence) = the angle the wave will be reflected at.
- Interactions of Waves Refraction
Refraction • The bending of waves. • Due to a change in speed. • Occurs when: • Enters a new medium • Enters it at an angle AND One side of the wave enters first and changes speed first, causing the wave to bend.
Diffraction • When a wave moves around a barrier • When a wave moves through a hole or opening in a barrier. OR
- Interactions of Waves Diffraction
Interference • Interaction between waves that meet (run into each other) • 2 types • Constructive (build up) • Destructive (tear down)
- Interactions of Waves Constructive Interference • When waves combine to make a wave with a larger amplitude. • When crest meets crest or trough meets trough. • Add their energies
The interference that occurs when waves combine to make a wave with a smaller amplitude. • Subtract their energies Destructive Interference
Standing Waves • A wave that appears to stand still in one place. • Actually 2 waves interfering as they pass through each other. • When an incoming wave meets a reflected wave at just the right frequency.
Standing waves cont. • Node: Point of zeroamplitude on a standing wave. • Min. energy • Antinode: Point of maximum amplitude on a standing wave. • Max. energy
Resonance • When external vibrations match an objects natural frequency • Increases the amplitude of the vibration