2. Reflection
• This is a
property of light
where light
waves bounce off
from a reflecting
surface.
3. Law of Reflection
The angle of
incidence is
equal to the
angle of
reflection as
measured
from the
normal.
4. Two kinds of Reflection
Specular Reflection
• Occurs when the surface
is very smooth such as a
mirror or polished floor
Diffuse Reflection
• Occurs when light hits a
rough or irregular
surface resulting to the
bouncing back of light
waves in different
directions.
7. Refraction
• Bending of light as it passes
from one medium to
another.
• As light refracts, its velocity
changes, its wavelength
increases or decreases, but
its frequency remains
constant.
8. Index of refraction (n)
• the ratio of velocities of light as it passes from a
vacuum into another medium.
𝑛 =
𝑐
𝑣
• Indices of Refraction for light in different mediums
are shown in your books.
9. Total Internal Reflection
- phenomenon
wherein the
incident rays
striking the
boundary of two
media are
reflected back
into its first
medium and the
bounding surface
acts like a perfect
reflector.
12. Diffraction
• When light waves
passes through an
obstacle, they
tend to bend
around the barrier
and spread out.
13. Diffraction
• The amount of bending
depends on the size of
the wavelength of light
to the size of the
opening.
• If the opening is much
larger than the light’s
wavelength, the
bending will almost be
unnoticeable.
14. Diffraction
• However, if the two
are closer in size or
equal, the amount
of bending is
considerable and
easily seen with the
naked eye.
15. Interference
• When two light waves from different coherent sources meet together, the
distribution of energy due to one wave is distributed by the other.
• Interference of light or optical interference is due to the superposition
of two light waves.
16. The Double-Slit Experiment
• In Thomas Young’s
Double-Slit experiment, he
made sunlight pass
through long parallel slits.
• The result was
“interference fringes”, light
and dark bands that
appeared on the screen
behind the slits
17. The Double-Slit Experiment
• When only one slit was
open, the pattern on the
screen was a diffraction
pattern, a fairly narrow
central band with
dimmer bands parallel to
it on each side.
• When both slits are
open, patterns of dark
and light bands showed
on the screen.
18. Principle of Superposition of Waves
•The resultant displacement at a point
is equal to the vector sum of the
displacements of different waves at
that point.
23. Polarized Light Waves
• Polarized light
waves are light
waves in which
the vibrations
occur in a single
plane.
• The most
common method
of polarization
involves the use of
a Polaroid filter.
25. Classifications of Polarization of Light
• Linearly polarized light wave – has an electric field that occurs
along a line.
• Circular polarized light wave – when light is composed of two
plane waves of equal magnitude but differing in phase.
• Right-circularly polarized – if the electric vector of the light coming toward
you appears to be rotating counterclockwise.
• Left-circularly polarized – if the electric vector appears to rotate clockwise.
• Elliptical polarized light wave - when two plane waves of differing
amplitude are related in phase by 90°.
Editor's Notes
Angle of incidence and angle od reflection happens on the same plane.
The smoothness or roughness of a surface depends on the wavelength of the EM Wave bouncing off from it.
Example, a red ray may produce diffuse rflection when incident upon by violet rays—diffusion.
Speed of light varies in different medium.
In a vacuum, its speed is 3.0x10^8 but in water its only 2.25x20^8
In refraction, two angles are formed—angle of incidence and angle of refraction.
In reflection, both angle happen on the same plane. Contrary to that, in refraction, these angles form in different planes.
Say that the incident ray produce an angle of refraction that is equal to 90 deg in the medium, we call this angle critical angle.
When you point hit a light from air to water at angle from the normal, light would bend to the water.
But when we increase the incident angle, it would come to a point that light would not bend to the water instead it would bounce back to the air (reflect) just like how a mirror works,
Another phenomenon that is a result of refraction is dispersion.
When light eneters the prism, it is refracted.
An example of refraction is a spoon placed in a glass of water, the spoon appears to be broken because of the refraction of light. The light from the spoon is refracted as it passes from the water to the glass then to the air causing it to be displaced.
Water having a curved surface acts as a magnifying glass, making the spoon appear bigger.
Light always travel in straight lines.
Circular, 2 plane waves with the same amplitude but different phase.
Elliptical, 2 plane waves of different amplitude but same in phase.
