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3) Diffraction: The bending of waves around the edge of a barrier

Reflection ~when an object or wave hits a surface through which it cannot pass, and then bounces back. http://paws.kettering.edu/~drussell/Demos/reflect/reflect.html Draw the angle of incidence and angle of reflection:

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3) Diffraction: The bending of waves around the edge of a barrier

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  1. Reflection ~when an object or wave hits a surface through which it cannot pass, and then bounces back. http://paws.kettering.edu/~drussell/Demos/reflect/reflect.html • Draw the angle of incidence and angle of reflection: • The Law of Reflection: The angle of reflection always equals the angle of incidence

  2. 2) Refraction: The bending of a wave due to a change in speed http://interactagram.com/physics/optics/refraction/ A wave is moving from one medium to another, and as it does so, one side of the wave begins to travel at a different speed than the other side does, causing it to bend.

  3. 3) Diffraction: The bending of waves around the edge of a barrier When a wave passes a barrier or moves through a hole it bends and spreads out http://projects.cbe.ab.ca/sss/science/physics/map_north/applets/waterdiffraction/waterdiffraction.html

  4. 4) Interference: 2 or more waves meet and have an effect on each other. Constructive Interference: Two waves combine to make a wave with a larger amplitude. http://www.sciencejoywagon.com/physicszone/09waves/ Destructive Interference: Two waves combine to make a wave with a smaller amplitude. http://www.surendranath.org/Applets/Waves/Twave02/Twave02Applet.html

  5. 5) Standing Waves: An incoming and reflected wave combine at the right places, making the wave appear to be standing in one place. This only occurs when the wave has a certain frequency http://www.sciencejoywagon.com/physicszone/09waves/

  6. How Does a Standing Wave Happen???? ~When any two waves meet INTERFERENCE occurs. ~With a standing wave, the incident wave hits a fixed point, becomes a reflected wave by bouncing back and then interferes or combines with the next incident wave. http://www.colorado.edu/physics/2000/microwaves/standing_wave1.html

  7. Nodes: the point of destructive interference : an amplitude of ZERO (crest-trough) Antinodes: the point of constructive interference (crest-crest or trough-trough) http://www.cdli.ca/courses/phys2204/unit04_org01_ilo11/b_activity.html http://www.youtube.com/watch?v=4PnlDAHW9co

  8. Lets think about it • What happened to the length of the wave when the drill sped up, i.e., when more energy is added? • What occurred to the wavelength when the drill was slowed?

  9. RESONANCE: the frequency of the vibrations traveling through an object match the objects natural frequency-forms a resonant standing wave. If vibrations of the same frequency are added together (constructive interference), and the amplitude of the objects vibrations increases. In other words, all things have a natural frequency and if we put energy into something at its natural frequency, the energy could continue to build up to very high levels.

  10. It’s also been noted that bridges and other physical structures can be affected by vibration. The Broughton Suspension Bridge that spanned the River Irwell in the UK collapsed on April 12, 1831 due to a mechanical resonance induced by troops marching over the bridge in step (that’s why soldiers break step when marching across a bridge).

  11. POP QUIZ!! • This is the name for when two waves combine to produce a wave with a larger amplitude. • The Broughton Suspension Bridge collapsed because the soldiers marched in step across it causing what? • This has nodes and antinodes. • Two tuning forks that can force each other make a noise have the same what? • Nodes are places where what type of interference is occurring? Constructive Interference Resonance Frequency Standing Wave Destructive Interference

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