di marunong c cubijano!!! hehehe

Refraction of Light
Refraction is the bending of a wave when it enters a medium where it's
speed is different. The refraction of light when it passes from a fast
medium to a slow medium bends the light ray toward the normal to the
boundary between the two media. The amount of bending depends on the
indices of refraction of the two media and is described quantitatively
by Snell's Law.

When a wave passes from one medium into another medium that has a
different velocity of propagation, a change in the direction of the
wave will occur. This changing of direction as the wave enters the
second medium is called REFRACTION. As in the discussion of
reflection, the wave striking the boundary (surface) is called the
INCIDENT WAVE, and the imaginary line perpendicular to the boundary is
called the NORMAL. The angle between the incident wave and the normal
is called the ANGLE OF INCIDENCE. As the wave passes through the
boundary, it is bent either toward or away from the normal. The angle
between the normal and the path of the wave through the second medium
is the ANGLE OF REFRACTION.

A refracted wave occurs when a wave passes from one medium into
another medium. What determines the angle of refraction?




ANSWERS TO QUESTIONS Q1. THROUGH Q48.

A1. Propagation means spreading out.
A2. A wave is a disturbance which moves through a medium.
A3. A means of transferring energy from one place to another.
A4. Sound waves, light waves, radio waves, heat waves, water waves.
A5. Transverse waves.
A6. Radio waves, light waves, and heat waves.
A7. A sound wave.
A8. A source, medium, and detector (receiver).
A9. A sequence of events, such as the positive and negative
alternation of electrical current.
A10. The space occupied by one cycle of a radio wave at any given
instant.
A11. The law of reflection states: The angle of incidence is equal
to the angle of reflection.
A12. When the incident wave is nearly parallel with the surface.
A13. When the incident wave is perpendicular to the surface. Also a
dull (or black) surface reflects very little regardless of the
angle.
A14. The density of the two mediums, and the velocity of the waves.
A15. The Doppler effect.
A16. Sonics.
A17. No. The average human ear cannot hear all sounds in the
infrasonic and ultrasonic regions.
A18. An amplifier.
A19. A source, medium, and detector (receiver).
A20. Noise and tones.
A21. Pitch, intensity, and quality.
A22. 20 Hz to 20 kHz.
A23. The amount of energy transmitted from a source.
A24. Quality.
A25. Velocity increases as density decreases and temperature
increases.
A26. Acoustics.
A27. Echo.
A28. Reverberation.

Vector form
Given a normalized ray vector v and a normalized plane normal vector
p, one can work out the normalized reflected and refracted rays: (note
that the actual angles è1 and è2 are not worked out)





Note: v and p must be in the same direction

The cosines may be recycled and used in the Fresnel equations for
working out the intensity of the resulting rays. During total internal
reflection an evanescent wave is produced, which rapidly decays from
the surface into the second medium. Conservation of energy is
maintained by the circulation of energy across the boundary, averaging
to zero net energy transmission.

Derivation
Snell's law may be derived from Fermat's principle, which states that
the light travels the path which takes the least time. By taking the
derivative of the optical path length, the stationary point is found
giving the path taken by the light. Alternatively, it can be derived
using interference of all possible paths of light wave from source to
observer - it results in destructive interference everywhere except
extrema of phase (where interference is constructive) - which become
actual paths. In a classic analogy by Feynman, the area of lower
refractive index is replaced by a beach, the area of higher refractive
index by the sea, and the fastest way for a rescuer on the beach to
get to a drowning person in the sea is to run along a path that
follows Snell's law.

Diffuse reflection

Diffuse reflectionMain article: Diffuse reflection
When light strikes a rough or granular surface, it bounces off in all
directions due to the microscopic irregularities of the interface.
Thus, an image is not formed. This is called diffuse reflection. The
exact form of the reflection depends on the structure of the surface.
One common model for diffuse reflection is Lambertian reflectance, in
which the light is reflected with equal luminance (in photometry) or
radiance (in radiometry) in all directions, as defined by Lambert's
cosine law.

Retroreflection

Working principle of a corner reflectorMain article: Retroreflector
Some surfaces exhibit retroreflection. The structure of these surfaces
is such that light is returned in the direction from which it came. A
simple retroreflector can be made by placing three ordinary mirrors
mutually perpendicular to one another (a corner reflector). The image
produced is the inverse of one produced by a single mirror.

A surface can be made partially retroreflective by depositing a layer
of tiny refractive spheres on it or by creating small pyramid like
structures (cube corner reflection). In both cases internal reflection
causes the light to be reflected back to where it originated. This is
used to make traffic signs and automobile license plates reflect light
mostly back in the direction from which it came. In this application
perfect retroreflection is not desired, since the light would then be
directed back into the headlights of an oncoming car rather than to
the driver's eyes

Complex conjugate reflection
Light bounces exactly back in the direction from which it came due
to a nonlinear optical process. In this type of reflection, not only
the direction of the light is reversed, but the actual wavefronts
are reversed as well. A conjugate reflector can be used to remove
aberrations from a beam by reflecting it and then passing the
reflection through the aberrating optics a second time.

[bearbeiden]
Neutron reflection
Materials that reflect neutrons, for example beryllium, are used in
nuclear reactors and nuclear weapons.

[bearbeiden]
Sound reflection
When a longitudinal sound wave strikes a flat surface, sound is
reflected in a coherent manner provided that the dimension of the
reflective surface is large compared to the wavelength of the sound.
In the theory of exterior noise mitigation, this phenomenon mildly
detracts from the concept of a noise barrier by reflecting some of
the sound into the opposite direction.

Quantum Interpretation
All interactions between light photons and matter are described as a
series of absorption and emission of photons. If one examines a
single molecule at the surface of a material, an arriving photon
will be absorbed and almost immediately reemitted. The `new' photon
may be emitted in any direction, thus causing diffuse reflection.

The specular reflection (following Hero's equi-angular reflection
law) is a quantum mechanical effect explained as the sum of the most
likely paths the photons will have taken. Light-matter interaction
is a topic in Quantum Electrodynamics, and is described in detail by
Richard Feynman in his book QED: The Strange Theory of Light and
Matter.

As the photon absorbed by the molecule may match energetic levels of
the molecule (Kinetic, Rotational, Electronic or Vibrational), the
photon may not be reemitted or alternatively may lose some of its
energy in the process. The emitted photon will have a slightly
different level of energy. These effects are known as Raman,
Brillouin and Compton scattering.

Reflection is the change in direction of a wave front at an interface
between two dissimilar media so that the wave front returns into the
medium from which it originated. Common examples include the
reflection of light, sound and water waves.

Reflection of light may be specular (that is, mirror-like) or diffuse
(that is, not retaining the image, only the energy) depending on the
nature of the interface. Whether the interfaces consists of dielectric-
conductor or dielectric-dielectric, the phase of the reflected wave
may or may not be inverted.

Total external reflection is an optical phenomenon where
electromagnetic radiation (e.g. visible light) can, at certain angles,
be totally reflected from an interface between two media of different
indices of refraction (see Snell's law). Total internal reflection
occurs when the first medium has a larger refractive index than the
second medium, for example, light that emerges from under water. The
optically more dense material (water in this case) is the "internal"
medium. For visible light, water has an index of refraction of 1.33
and for air it is very close to 1. For vacuum the index of refraction
is exactly 1 for all wavelengths.

For X-rays, however, all materials have indices of refraction slightly
below 1. This entails that total reflection of X-rays only can occur
when they travel through vacuum and impinge on a surface (at a small
glancing angle). Since this kind of total reflection takes place
outside of the material it is termed total external reflection.

Retrieved from "http://en.wikipedia.org/wiki/Total_external_reflection"

Derivation
Snell's law may be derived from Fermat's principle, which states that
the light travels the path which takes the least time. By taking the
derivative of the optical path length, the stationary point is found
giving the path taken by the light. Alternatively, it can be derived
using interference of all possible paths of light wave from source to
observer - it results in destructive interference everywhere except
extrema of phase (where interference is constructive) - which become
actual paths. In a classic analogy by Feynman, the area of lower
refractive index is replaced by a beach, the area of higher refractive
index by the sea, and the fastest way for a rescuer on the beach to
get to a drowning person in the sea is to run along a path that
follows Snell's law.

In telecommunications, the reflection coefficient is the ratio of
the amplitude of the reflected wave to the amplitude of the incident
wave. In particular, at a discontinuity in a transmission line, it
is the complex ratio of the electric field strength of the reflected
wave to that of the incident wave. This is typically represented
with a à (capital gamma).

The reflection coefficient may also be established using other field
or circuit quantities.

The reflection coefficient is given by the equations below, where Z1
is the impedance toward the source, Z2 is the impedance toward the
load:


The absolute magnitude of the reflection coefficient (designated by
vertical bars) can be calculated from the standing wave ratio, SWR:


The reflection coefficient is displayed graphically using a Smith
chart.

Source: from Federal Standard 1037C in support of MIL-STD-188

[edit]
Seismology
See: reflection seismology
[edit]
Optics
Main article: Fresnel equations
In optics, both intensity and amplitude reflection coefficients are
used. Typically, the former are represented by a capitol R, while
the latter are represented by a lower-case r.

Retrieved from "http://en.wikipedia.org/wiki/Reflection_coefficient"

History
Snell's law was first discovered and described by Ibn Sahl in a
manuscript written c.984 [1], who used it to work out the shapes of
anaclastic lenses (lenses that focus light with no geometric
aberrations). It was discovered again by Thomas Harriot in 1602 [2],
who did not publish his work. In 1621, it was discovered yet again by
Willebrord Snell, in a mathematically equivalent form, but unpublished
during his lifetime. René Descartes independently derived the law in
terms of sines in his 1637 treatise Discourse on Method, and used it
to solve a range of optical problems. In French, Snell's Law is
called "la loi de Descartes" or "loi de Snell-Descartes".

In optics, reflectivity is the reflectance (the ratio of reflected
power to incident power, generally expressed in decibels or
percentage) at the surface of a material so thick that the
reflectance does not change with increasing thickness; i.e., the
intrinsic reflectance of the surface, irrespective of other
parameters such as the reflectance of the rear surface. The concept
is of some importance in telecommunications.

Surface reflectance may be subdivided into diffuse or Lambertian
reflectance and specular reflectance. The apparent reflectance for
an ideal Lambertian surface is independent of the observer's angle
of view. This contrasts with a shiny (specular) surface, where the
apparent brightness is highest when the observing angle is equal and
opposite to the source angle. Most real objects have some mixture of
diffuse and specular qualities.

Source: from Federal Standard 1037C

Note: In climatology, reflectivity is called albedo.

Retrieved from "http://en.wikipedia.org/wiki/Reflectivity"

Total internal reflection
When moving from a dense to a less dense medium (i.e. n1 > n2), it is
easily verified that the above equation has no solution when è1
exceeds a value known as the critical angle:


When è1 > ècrit, no refracted ray appears, and the incident ray
undergoes total internal reflection from the interface.

A simple gravity pendulum or bob pendulum (plural pendulums or
pendula), is a weight on the end of a rigid rod (or a string/rope),
which, when given an initial push, will swing back and forth under the
influence of gravity over its central (lowest) point.

The pendulum was discovered by Ibn Yunus al-Masri during the 10th
century, who was the first to study and document its oscillatory
motion. Its value for use in clocks was introduced by physicists
during the 15th century.

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is a phenomenon that causes the seperation of a wave into spectral
components with different wavelengths, due to dependence of the wave's
speed on it's wavelength. it is most often described in lightwaves,
though it may happen to any kind of wave that interacts with a medium
or can be confined to wave guide, such as sound waves.

The reflection coefficient is used in physics and electrical
engineering when wave propagation in a medium containing
discontinuities is considered. A reflection coefficient describes
either the amplitude or the intensity of a reflected wave relative to
an incident wave. The reflection coefficient is closely related to the
transmission coefficient.

Different specialties have different applications for the term.

the distance between two consecutive (one after another) crest or
troughs of a wave it is called the WAVELENGTH. The wavelength can be
measured from any point on a wave as long as it is measured to the
point on the nextwave.

BALIW C PALMO!!!!!!!!!!!!!!!!!

Table of Opticks, 1728 CyclopaediaOptics (appearance or look in
ancient Greek) is a branch of physics that describes the behavior
and properties of light and the interaction of light with matter.
Optics explains and is illuminated by optical phenomena.

The field of optics usually describes the behavior of visible,
infrared, and ultraviolet light; however because light is an
electromagnetic wave, analogous phenomena occur in X-rays,
microwaves, radio waves, and other forms of electromagnetic
radiation. Optics can thus be regarded as a sub-field of
electromagnetism. Some optical phenomena depend on the quantum
nature of light and as such some areas of optics are also related to
quantum mechanics. In practice, the vast majority of optical
phenomena can be accounted for using the electromagnetic description
of light, as described by Maxwell's Equations.

Optics, however, as a field is often considered largely separate
from the physics community. It has its own identity, societies, and
conferences. The pure science aspects of the field are often called
optical science or optical physics. Applied optical sciences are
often called optical engineering. Applications of optical
engineering related specifically to illumination systems are called
illumination engineering. Each of these disciplines tends to be
quite different in its applications, technical skills, focus, and
professional affiliations.

Because of the wide application of the science of "light" to real-
world applications, the areas of optical science and optical
engineering tend to be very cross-disciplinary. Optical science is a
part of many related disciplines including electrical engineering,
physics, psychology, medicine (particularly ophthalmology and
optometry), and others. Additionally, the most complete description
of optical behavior, as known to physics, is unnecessarily
complicated for most scenarios so particular simplified theories are
used. These limited theories adequately describe subsets of optical
phenomena while ignoring behavior irrelevant and/or undetectable to
the system of interest.

Optics (appearance or look in ancient Greek) is a branch of physics
that describes the behavior and properties of light and the
interaction of light with matter. Optics explains and is illuminated
by optical phenomena.

Refraction is the change in direction of a wave due to a change in its
velocity. This is most commonly seen when a wave passes from one
medium to another. Refraction of light is the most commonly seen
example, but any type of wave can refract when it interacts with a
medium, for example when sound waves pass from one medium into another.

Reflection is the change in direction of a wave front at an interface
between two dissimilar media so that the wave front returns into the
medium from which it originated. Common examples include the
reflection of light, sound and water waves.

Lightwave has long been known for its excellent rendering abilities
and unusual user interface (for example, icons are not used; instead
functions are all given descriptive titles). Like many other 3D
packages Lightwave is composed of two parts, an object modelling
environment where 3d models or meshes are created and an animation
environment where models are arranged and animated for render. Unlike
most other packages these two parts are stand-alone programs. There is
also a separate rendering application which can be run on multiple
machines.

Light is electromagnetic radiation with a wavelength that is visible
to the eye (visible light) or, in a technical or scientific context,
electromagnetic radiation of any wavelength. The three basic
dimensions of light (i.e., all electromagnetic radiation) are:

Aberration in optical systems (lenses, prisms, mirrors or series of
them intended to produce a sharp image) generally leads to blurring of
the image. It occurs when light from one point of an object after
transmission through the system does not converge into (or does not
diverge from) a single point. Instrument-makers need to correct
optical systems to compensate for aberration. The articles reflection,
refraction and caustic discuss the general features of reflected and
refracted rays.