INTRODUCTIONTO LIGHTS

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

Light Waves vs. Sound Waves SOUND WAVES

Are compressional, or longitudinal Sound waves need a medium to travel;

they cannot travel through empty space.

BEHAVIORAL CHARACTERISTICS 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. 

REFLECTIONAll 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.

REFRACTIONAll waves are known to undergo refraction when they pass from one medium to another medium. That is, when a wave front crosses the boundary between two media, the direction that the wave front 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.

DIFFRACTIONIt 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.

References: http://

camillasenior.homestead.com/optics3.html

http://www.physicsclassroom.com/Class/light/u12l1b.cfm

PHYSICS OF LIGHT

DE LA LUNA, MARGARETTE A. QUIROS, ELLYSA CHARISE M.

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.

Introduction• The wavelength of a light wave is inversely proportional to its

frequency.

Introduction• "Is light a wave or a stream of particles?“• The fact is that light exhibits behaviors that are characteristic of

both waves and particles.• Albert Einstein discovered the nature of light as stream of

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.

BEHAVIOR OF LIGHT• 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.

BEHAVIOR OF LIGHT• 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.

BEHAVIOR OF LIGHT• 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 shorter

wavelength scatter more• Our eye sensitivity to the

blue color is much stronger than that to violet.

RAYLEIGH SCATTERING 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

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.

References

• 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

ABSORPTIONLIGHT

O We have previously learned that:O visible light waves consist of a

continuous range of wavelengths or frequencies. 

O visible light waves consist of a continuous range of wavelengths or frequencies. 

O The light wave could be absorbed by the object, in which case its energy is converted to heat. 

O The light wave could be reflected by the object. 

O And the light wave could be transmitted by the object. 

Atoms and molecules contain electrons.

O When a light wave with that same natural frequency impinges upon an atom, then the electrons of that atom will be set into vibrational motion. 

O If a light wave of a given frequency strikes a material with electrons having the same vibrational frequencies, then those electrons will absorb the energy of the light wave and transform it into vibrational motion. During its vibration, the electrons interact with neighboring atoms in such a manner as to convert its vibrational energy into thermal energy. 

O absorption depends on the electromagnetic frequency of the light being transmitted (i.e. the color) and the nature of the atoms of the object. 

O If they are complementary, light will be absorbed; if they are not, then the light will be reflected or transmitted. In most cases, these processes occur simultaneously and to varying degrees, since light is usually transmitted at various frequencies. 

REFLECTION MERCADO, DAN RHYAN U.2013122125

Reflection of Light

Reflection is when light bounces off an object. If the surface is smooth and shiny, like glass, water or polished metal, the light will reflect at the same angle as it hit the surface. This is called Specular reflection.

Diffuse reflection is when light hits an object and reflects in lots of different directions. This happens when the surface is rough. Most of the things we see are because light from a source has reflected off it.

SPECULAR REFLECTION

DIFFUSE REFLECTION

Law of Reflection and Angle of ReflectionA ray of light hitting the surface (incident ray) comes in at an angle, which is called the angle of incidence. The ray of light bounces off the surface (reflected ray) at an angle, which is called the angle of reflection.

According to the law of reflection, the angle of incidence is equal to the angle of reflection.

Light in ArchitectureThe quality of lighting in a space defines its character and creates impressions. The human eye perceives its form through the incidence and reflection of light and in that way acquires information about the ambiance in a given place. Visual impressions are interpreted in our brains and put in context to create emotions that move us to take particular actions.

REFERENCES:

• http://study.com/academy/lesson/angle-of-reflection-definition-formula-quiz.html• http://sciencelearn.org.nz/Contexts/Light-and-Sight/Science-Ideas-and-Concepts/

Reflection-of-light• http://lgg.epfl.ch/publications/2012/caustics/ArchitecturalCaustics_AAG.pdf• http://light2015blog.org/2015/01/27/light-in-architecture/