MOD 5 LECTURE
WAVE - MATTER INTERACTIONS
In this lecture you will:
learn about interference in sound and light
WAVE - MATTER INTERACTIONS OVERVIEW
Here is a good source of information on
the science of sound. We will study only a few of them in conjunction
with what is happening to light in interference, reflection, refraction,
diffraction, and reflection. At the end we will take up the doppler effect
of both sound and light.
Here is an overall view of the various
areas of light and vision that are studied by science. We have already
looked at quantum properties of light. In this lecture we will look
SUMMARY OF WAVE - MATTER INTERACTIONS
|Type of waves
into each other
||Hit and bounce off surfaces
||acoustics: echoes and reverberations
||mirrors, colors, shiny and matte
||Enter clear materials and bends
||rumble of thunderstorms
||lenses, diamonds, rainbows
||Bend around solid or little slit
||how we hear around a post
||slits, rainbow effect on CD or DVD
INTERFERENCE: IN GENERAL
|When waves run into each other, they can
amplify or cancel each other out
– if the waves are synchronized, crest
to crest, trough to trough, then they amplify
— if the waves are crest to trough, they
- in between they cancel or amplify to
|EXAMPLE: in badly constructed amphitheaters
there are seats where the sound comes together and cancels. This
is also the reason that the speakers of "surround sound" systems have to
be carefully placed.
What we hear is softer or louder
HOW WE HEAR SOUND WAVES
|1. Something vibrates and creates a sound
2. The sound wave travels to the ear and
is collect by the outer ear.
3. The sound wave then moves into the
4. At the end of the ear canal, the sound
waves bump against the eardrum.
5. The ear drum vibrates with these sound
6. The vibration moves tiny bones in the
7. These bones carry vibrations into the
inner ear to a fluid filled tube called the cochlea.
8. The fluid inside vibrates a series
of tiny hairs called cilia, which are attached to auditory nerves.
9. The movement of cilia stimulates nerve
cells, and send signals to the brain via the auditory nerve.
10. The brain processes these signals
into the sounds we hear
|"The wave properties of light lead to
interference, but certain conditions of coherence must be met for these
interference effects to be readily visible. "
SUMMARY OF EFFECTS
|loud and soft areas of sound in concerts
|bright or dim areas lined up in a row
on a surface
||light interference using lasers