Review Waves

Wave Pulse = short burst of Energy

2 Types of Traveling Waves Longitudinal Waves Medium moves Parallel to the direction energy travels (sound) Transverse Waves SHOW Family Tree structure: see next hidden slide Medium moves Perpendicular to the direction energy travels

Slinky Demo – Transmitting a wave “Pulse” 1) Pulse Travels (energy) 2) Pulse Refection (2 types) 3) Vary f 4) Standing Waves 5) 2 Wave types

Wave “Phase” and “Phase Difference” Each wave cycle has 360o Each point on the wave is a phase of the wave Points on the wave 360o apart are said to be in “phase” (or 720o,1080o, etc.) Points on the wave 180o apart are said to be exactly out of “phase” (or 540o,900o, etc.) Here, show via 2 Spring example when two masses are exactly IN & OUT of phase

Displacement vs Position Graphs Copy this graph as it’s sketched on the chalkboard Crest = top of wave Trough = bottom of wave Wavelength = distance of one complete wave cycle Amplitude = energy of a mechanical wave (ex. Loudness for sound) D [m] Corresponding to the ripple tank... + Wavelength [] crest crest amplitude x [m] trough trough Line of Equilibrium -

2 Types of Interference: Constructive: waves add up to become stronger Destructive: waves add up to become weaker

Thick lines = Crests Thin lines = Troughs Thus: Red dots = constructive interference (2 crests or 2 troughs) And: Blue dots = destructive interference (Meeting of a crest & trough)

Resonance All objects will oscillate (vibrate)at their own natural frequency

Standing Waves: DRAW & LABEL On a standing wave, wave “appears” to be fixed in space, changing in amplitude only Antinode = spot of total constructive interference (max. amplitude) Black Line = Resultant Standing Wave Node = spot of total destructive interference (no amplitude)

Light = EM (Electromagnetic Wave) Not all light is visible

Speed of light

UG: Describe the Nature of Reflection The Reflection of Light Demo = the "Normal" Angle measured from the Normal Incident angle, = Reflected angle Law of Reflection SUNY

Diffraction = Waves Spreading Circularly behind barrier Mechanical & EM Waves both Diffract

Incident Ray Reflected Ray Refracted Ray

If light enters a more dense medium Bends closer to the normal!

Light entering a less dense medium It bends away from normal

n1 sinθ1 = n2 sinθ2