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Transcript of Sound waves!!!
Light travels in straight lines we call light rays.
We represent these rays using arrows
Light requires no medium; yet it is affectyed by the ones that it encounters.
The light may be absorbed
Light may be transmitted
Light may be reflected
If this is the case, absorbed energy increases the motion of the molecules that absorb it (temp. increase)
If this occurs, energy passes through (its speed may be affected)
Light that is reflected is forced to bounce back. The energy is forced to change course
For 100% of energy to be reflected is unlikely
What happens when waves encounter a new medium.
They are very useful in understanding reflection and refraction concepts
a percentage of the energy is reflected...some is absorbed
The Law of Reflection
The Law of Reflection states that the angle of incident light rays will be equal to the angle of refeclting light rays.
This type of reflection occurs when surfaces are smooth
Incident parallel light rays reflect parallel.
This is due to the fact that all light rays have the same incident angles!
This type of reflection accounts for the majority of what you see every day
This is due to the fact that most surfaces are not smooth!!!
Incident parallel light rays reflect out in thousands of different angles
This is due to the fact that each light ray may not have the same incident angle.
Types of mirrors
Object size equals image size
Image is always reversed
Object distance and image distance from mirror are the same
Object is always smaller
Image is awlays reversed
Object distance and image distance are never the same
Widened field of view
Image size depends on location of object
Images may be magnified
Object distance and image distance are not the same
Images may be inverted
total internal reflection
Color dispersion in prisms
Refraction of light
Refraction of sound
Refraction occurs when:
waves pass into different media
On a hot day...
On a cool day...
Sound carries better on a....
When the sound waves are refracted away form the ground...where could you go to hear them?
Two causes of refraction?
Light travels in straight lines unless...
Remember Speed of light changes depending on the medium it is in....
Ethyl Alcohol 1.36
Crown Glass 1.52
Light Flint Glass 1.58
Dense Flint Glass 1.66
Gallium phosphide 3.50
waves travel through media with varying densities
Sound wave bends down!!!
Sound wave bends up!!!
Materials refract light at different angles each angle gives each materail a different refractive index
Because our brain interprets light as having come to our eyes in straight lines, refracted images appear to be in places where they are not.
1. Light of different frequencies travels at different speeds in a medium
5. Dispersion of light allows us to see the spectrum
4. Light that is bent twice at nonparallel boundaries exagerates this difference
3. Violet is 1% slower in a transparent medium. ----> it bends more than red
2. Different frequencies refract at different angles
1. A rain drop has nonparallel sides
2. It is capable of producing a dispersion pattern
For a rainbow to occur:
1. the light source must be behind you
2. there must be water droplets in the sky
3. the orientation to see the rainbow: 42 degrees
4. Rainbows are not actually bows...they are circles that get interupted by the ground.
This is the critical angle!!!!
100% of light is reflected!!!
No light escapes!!!
Lighter than copper
Cheaper than copper
Faster than copper
Used in medicine!
Used in telecomunications!
Used in design!