Group 1: Behavioral Characteristic of Light
Physics of Light
Transmission, Reflection and Absorption
Leader: Marcelo, Queenie Rose
Members: De la Luna, Margarette
Landicho, Vichael
Mercado, Dan
Montaña, Juan Christian
Quiros, Ellysa Charise
Sulit, Dana Allyssa
I. BEHAVIORAL CHARACTERISTIC OF LIGHT
What is light?
Light is a form of energy.
Light has properties of both a wave and a particle.
Light waves move as transverse waves.
These waves move extremely fast in straight paths called rays
Light waves do not need a medium through which to move.
Light waves are electromagnetic waves
Light Waves vs. Sound Waves
LIGHT WAVES
It move as transverse waves
It do not need a medium to travel; they can travel through empty space
SOUND WAVES
Are compressional, or longitudinal
Sound waves need a medium to travel; they cannot travel through empty
space.
Behavioral Characteristic of Light
Light exhibits certain behaviors that are characteristic of any wave and would
be difficult to explain with a purely particle-view. Light reflects in the same manner
that any wave would reflect. Light refracts in the same manner that any wave would
refract. Light diffracts in the same manner that any wave would diffract. Light
undergoes interference in the same manner that any wave would interfere. And
light exhibits the Doppler effect just as any wave would exhibit the Doppler effect.
Light behaves in a way that is consistent with our conceptual and mathematical
understanding of waves. Since light behaves like a wave, one would have good
reason to believe that it might be a wave.
Reflection
All waves are known to undergo reflection or the bouncing off of an
obstacle. Most people are very accustomed to the fact that light waves also
undergo reflection. The reflection of light waves off of a mirrored surface results in
the formation of an image. One characteristic of wave reflection is that the angle at
which the wave approaches a flat reflecting surface is equal to the angle at which
the wave leaves the surface. This characteristic is observed for water waves and
sound waves. It is also observed for light waves. Light, like any wave, follows the
law of reflection when bouncing off surfaces.
Refraction
All waves are known to undergo refraction when they pass from one medium
to another medium. That is, when a wavefront crosses the boundary between two
media, the direction that the wavefront is moving undergoes a sudden change; the
path is "bent”.
Refraction is the bending of light rays when passing through a surface
between one transparent material and another.
This behavior of wave refraction can be described by both conceptual and
mathematical principles. First, the direction of "bending" is dependent upon the
relative speed of the two media. Second, the amount of bending is dependent upon
the actual speeds of the two media on each side of the boundary.
These equations are based upon the speeds of the wave in the two media
and the angles at which the wave approaches and departs from the boundary.
Light, like any wave, is known to refract as it passes from one medium into another
medium.
Diffraction
It involves a change in direction of waves as they pass through an opening or
around an obstacle in their path.
When light encounters an obstacle in its path, the obstacle blocks the light
and tends to cause the formation of a shadow in the region behind the obstacle.
Light does not exhibit a very noticeable ability to bend around the obstacle and fill
in the region behind it with light. Nonetheless, light does diffract around obstacles.
In fact, if you observe a shadow carefully, you will notice that its edges are
extremely fuzzy.
Sources:
http://www.physicsclassroom.com/class/light/Lesson-1/Wavelike-Behaviors-of-
Light
II. PHYSICS OF LIGHT
Introduction
• Light is a transverse, electromagnetic wave that can be seen by humans.
• Light is sometimes also known as visible light to contrast it from "ultraviolet
light" and "infrared light".
• The amplitude of a light wave is related to its intensity.
-Intensity is the absolute measure of a light wave's power density.
-Brightness is the relative intensity as perceived by the average human
eye.
• The wavelength of a light wave is inversely proportional to its frequency.
• "Is light a wave or a stream of particles?"
• The fact is that light exhibits behaviors that are characteristic of both waves
and particles.
• In 1678, Christiaan Huygens (1629–1695) he argued in favor of the wave
nature of light. Huygens stated that an expanding sphere of light behaves as
if each point on the wave front were a new source of radiation of the same
frequency and phase.
BEHAVIOR OF LIGHT
• Reflection is the change in direction of a wavefront at an interface between
two different media so that the wavefront returns into the medium from
which it originated.
• The law of reflection says that for
specular reflection the angle at
which the wave is incident on the
surface equals the angle at which it is
reflected. Mirrors exhibit specular reflection.
• Refraction of waves involves a change in the direction of waves as they
pass from one medium to another. Refraction, or the bending of the path of
the waves, is accompanied by a change in speed and wavelength of the
waves.
• If the medium (and its properties) is changed, the speed of the waves is
changed.
• The most significant property of water that would affect the speed of waves
traveling on its surface is the depth of the water. Water waves travel fastest
when the medium is the deepest. Thus, if water
waves are passing from deep water into shallow
water, they will slow down.
• Waves traveling from the deep end to the
shallow end can be seen to refract (i.e., bend),
decrease wavelength (the wavefronts get closer
together), and slow down (they take a longer time to travel the same
distance). When traveling from deep water to shallow water, the waves are
seen to bend in such a manner that they seem to be traveling more
perpendicular to the surface. If traveling from shallow water to deep water,
the waves bend in the opposite direction.
• Reflection involves a change in direction of waves when they bounce off a
barrier; refraction of waves involves a change in the direction of waves as
they pass from one medium to another; and diffraction involves a change in
direction of waves as they pass through an opening or around a barrier in
their path.
What can a light wave do when it encounters matter?
• REFLECTION
-specular reflection of light by a mirror
-diffuse reflection of the light in this room off all the other students
-reflection is re-radiation of light by the electrons in the reflecting material
• ABSORBED
-Cyan light shining on a red apple is absorbed by electrons in the apple.
A light wave shining on molecules in the air or plastic or other “transparent”
materials can be
• SCATTERED
-Light ray moves over to the side in all directions rather than forward,
backward or being absorbed.
-Intensity of the scattered light can depend on wavelength
RAYLEIGH SCATTERING
• Light waves with longer
wavelength scatter more
• Our eye sensitivity to the blue
color is much stronger than that
to violet.
• Think of white light from sun as a
mixture of R, G and B. Blue is scattered the most so sky looks blue when we
look away from the sun. For same reason sun looks yellow (red + green)
More atmosphere allows next shortest wavelengths (green) to scatter so
sunset looks red.
SOURCES:
Google Images
The Physics Classroom, 2015
Elert, Glenn (2015), The Physics Hypertextbook
Staroscik, Andrew (2015) Science Prime
III. TRANSMISSION, REFLECTION AND ABSORPTION
A. TRANSMISSION
Transmission coefficient
• The transmission coefficient is used in physics and electrical engineering when wave propagation in a medium containing discontinuities is considered.
• A transmission coefficient describes the amplitude, intensity, or total power of a transmitted wave relative to an incident wave.
• In optics, transmission is the property of a substance to permit the passage of light, with some or none of the incident light being absorbed in the process.
• The transmission coefficient is a measure of how much of an electromagnetic wave (light) passes through a surface or an optical element.
These are the definitions stated in Wikipedia. Our topic is more of how the light works or simply optics. Optics is one of the branches of physics.
As it is bounded by the laws of physics, its properties are somehow tricky compared to other waves as it is now considered both wave and a particle.
In relation to architecture, a background about how light works is very important for us, architects (potential architects), to know about. Light is a major component for a building. It greatly affects the way you arrange the fenestration of the openings, the way you arrange spaces considering the amount of light needed, the number of lights and how strong the light should be, and how to conserve by using natural lighting.
In this part of study about light, my discussion is more of how a light works. Light is both wave and particle that can use medium or no medium (vacuum). When the light hits an object there are three conditions that occur: reflection, absorption, and transmission.
Transmission is simple. If the light particles didn’t bounce or reflect, didn’t get absorbed and passes through an object that is transmission.
One good of example of light transmission is refraction of light. When you dip a pencil into water, the pencil seems to be bent. The light changes direction as it passes through another medium, from air to water. Another example of it is prism. The white light passes through the prism; it disperses and radiates rainbow colors. For simpler example: a light passing through a glass.
For the example of pencil bending in the water, it is called refraction. Light might behave different to different mediums.
Sources:
• http://www.scratchapixel.com/old/lessons/3d-basic-lessons/lesson-14-interaction-light-matter/optics-reflection-and-refraction/
• http://www.physast.uga.edu/~rls/astro1020/ch4/ovhd.html
• https://en.wikipedia.org/wiki/Transmission_coefficient
QUESTIONNAIRES:
1. It is the bending of light rays when passing through a surface between one
transparent material and another.
A. Refraction
B. Reflection
C. Diffraction
D. Polarization
2. It involves a change in direction of waves as they pass through an opening or
around an obstacle in their path.
A. Refraction
B. Reflection
C. Diffraction
D. Polarization
3. Why is the sky blue?
A. Because of scattering of short-wavelength blue light coming from the Sun
B. Because of light absorption similar to that in color filters
C. A & B
D. Because of dispersion and total internal reflection
E. None of the above
4. Without Rayleigh scattering the Sky would be?
A. Red
B. Green
C. Blue
D. Black
E. White
5. Is light a wave or a stream of particles?
A. Wave
B. Particles
C. A &B
D.None of the Above
6. In architecture, which material does not block the transmission of light
greatly?
A. Glass
B. Concrete
C. Wood
D. Steel
7. What behavior of light that makes a pencil seemingly bending when dip into
the water?
A. Reflection
B. Absorption
C. Refraction
D. Water bending
8. According to the law of reflection, the angle of incidence is _______to the
angle of reflection.
A. Directly Proportional
B. Inversely Proportional
C. Equal
9. Reflection is when light hits an object and reflects in lots of different
directions. This happens when the surface is rough.
A. Spectral
B. Diffuse
C. Specular
D. Mirror
10.The ray of light hitting a surface that comes in at an angle, which is called the
angle of incidence.
A. Incident Ray
B. Sun Rays
C. Reflected Ray