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