WAVE PHENOMENA

Reflection at an Angle

Normal

Ray of light, or “ray” of sound at an angle to reflector

Virtual Ray

Incident angle

reflected angle

i

r

i r

mirror

Think about this next time you play pool

Normal is drawn perpendicular to boundary

Refraction: bending of a wavefront at a boundary between two media, due to the change in velocity

Refraction

water

air

air

water

2

1Incoming wave

Slower velocity

Helpful Analogy: Marching Band

Firm Ground

Muddy Mess

Helpful Analogy: wheel on an axel

Firm Ground

Muddy Mess

DiffractionIf a sound wave hits a door opening, the sound will bend/spread

d

Spreading will be the most for…

Small opening relative to the wavelength.

So… smaller the opening , the morediffaction and the longer thewavelength the more diffraction.

Diffraction

d

• Larger barrier with smaller gaps relative to the wavelength.

• So… larger the barrier = smaller gaps, = more diffaction and again, the longer the

• wavelength the more diffraction.

Spreading will be the most for…

http://rt210.sl.psu.edu/phys_anim/waves/indexer_waves.html

http://paws.kettering.edu/~drussell/Demos/superposition/superposition.html

INTERFERENCE OF WAVESThe principle of superposition may be applied to waves whenever two (or more) waves are travelling through the same medium at the same time. The waves pass through each other without being disturbed.

Constructive interference: Point where two waves meet in phase to produce a wave of larger amplitude.

Destructive interference: Point where two waves meet out of phase in order to produce waves of smaller amplitude.