Waves can interact with other waves, other objects, or change
medium (travel through different substances) When a wave meets a
new surface or boundery, the wave reflects When a wave passes the
edge of an object or passes through an opening, the wave diffracts
When a wave passes from one medium to another at an angle, it will
refract
Slide 3
Reflection is the bouncing back of a wave when it hits a
surface or boundary that is hard enough that it cant travel
through. Examples: water waves bouncing off of a boat, images in a
mirror (and glass or very still water), echos. Light obeys the Law
of Reflection The angle of incidence will equal the angle of
reflection
Slide 4
Flat Surfaces (like mirrors) Every single incident ray will hit
at the same angle, and bounce off at the same angle Rough Surfaces
(like water or frosted glass) Every single incident ray will hit at
a different angle, and scatter when they reflect
Slide 5
Diffraction: When waves pass the edge of an object, or reach an
opening, they will bend or spread: spread out as if they were
created there (for small openings) bend around the object (when
waves pass an edge)
Slide 6
Diffraction: When waves pass the edge of an object, or reach an
opening, they will bend or spread: Wind bends around this bottle to
blow out the candle
Slide 7
Slide 8
Refraction: The bending of waves when they pass from one medium
to the next Occurs when waves reach a new medium (that it can
travel through) at an angle. Medium = the material the wave is
traveling through Each time a wave reaches a new medium, they are
deflected (change direction) as they change speed The pencil looks
broken because of refraction: The light traveling to/from the part
of the pencil out of the water does not ever change speeds. The
light that travels to/from the part of the pencil in the water has
to change speeds (and changes angles) as it enters the water. This
causes light from each end to reach your eye at different
angles.
Slide 9
Different substances have different angles of refraction ie:
Waves bend/change directions at different angles when they enter
that specific substance This is because waves travel at different
speeds in different substances The slower light travels through an
object, the more light will bend and change direction when it
enters it
Slide 10
A laser and a glass cube Only wavelength, so it cant separate
into different wavelengths - That single wavelength slows down in
the glass cube to the left White Light and a PRISM White light is
made of ROYGBIV, many different wavelengths. It can separate into
different wavelengths - Each wavelength slows down at a different
rate, separating in the prism to the right
Slide 11
Light slows down when it enters a prism and bends down when it
strikes at this angle. Each wavelength of light slows down and
bends differently. Violet end slows down more than the red end, so
it bends more. When light exits the prism, it speeds back up and
bends down again.
Slide 12
Water will do the same thing it will refract light. When light
enters water, it will slow down (or bend) This causes objects
underwater to appear as if they are somewhere else. The light is
tricking your eye.
Slide 13
Water will do the same thing it will refract light.
Slide 14
So this is a polymer ball. Why does it disappear in water? It
has the same angle of refraction as water, so the light never
changes direction
Slide 15
Sometimes waves will interact with other waves Interference:
When several waves are in the same location, they combine to
produce a single, new wave that is different than the original wave
Once the waves pass through each other, they will return to their
original shape and continue on their path. 2 types Constructive
(add to each other) Destructive (cancel each other out)
Slide 16
When the CREST of one wave overlaps the CREST of another wave
the waves reinforce each other These wave are also called in phase
When this happens, the amplitude INCREASES
When the CREST of one wave overlaps the TROUGH of another wave,
the resulting wave has a SMALLER amplitude than the larger of the
two original waves When this happens, the waves can even cancel out
These wave are also called out of phase
A lens is an optical device with symmetry that transmits AND
refracts light We have 2 types of lenses: Convex (converging) and
concave (diverging) We can either use: A Simple Lens: one lens
Examples: reading glasses, magnifying glass, your retina A Compound
Lens: uses more than one lens Examples: telescope, microscope,
cameras, etc
Slide 23
Lenses can either be: Convex (converging) OR Concave
(diverging)
Slide 24
An eye that can see at 20/20 vision will allow light to focus
directly at the back of the retina. If you dont see 20/20, your
focal point is not directly on the retina, and you get a blurry
image
Slide 25
To correct nearsighted eyes (myopia), you use concave lenses
They move the focal point backward To correct farsighted eyes
(hyperopia), glasses will be made with convex lenses They move the
focal point forward.