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The Illusion Of A Mirage
What makes your brain tick?
According to researchers, the parts of your body, if you don't use it you lose
it, particularly your brain. The more you use it, the more logic & brainier you
are, could that be true???
The Mirage Illusions
The illusion of a mirage happens when we see a wavy or shimmering effect over a
hot pavement due to the various least-time paths of light passes through varying
temperature and density of air, the reflected least-time paths of light actually
curves (or bends) cause by changes in speed, a mirage can be photographed as
it's not an illusion to the eye.
The fact that we can see a wavy or shimmering effect, say over a hot stove or
over a hot road surface is due to the various least-time paths of light passing through varying
temperature and density of hot air in the vicinity makes a mirage illusion.
The illusion of a bending stick for example, partly immersed in water or a
fish appear near the surface of water due to refractions, submerged
objects are magnified, such as objects submerged 4 meters deep in the water, in our eyes appear 3 meters only, due to light in water travel @ 75% the speed of C.
Most transparent materials are in the ultraviolet end of the frequency spectrum,
but higher frequency of visible light travels more slowly than lower
frequencies. For example, violet travels about 1% slower than the slow red frequency of light.
Different frequencies of light travel differently in transparent materials,
and refract (bends) at a different least-time were noticeable, particularly
the separation of light-colours in a prism. This separation of light into
colours arranged according to their frequency is called dispersion.
Are Rainbows Bow or Circle ?
Rainbows appear as the sun is shining in one part of the sky and rain
drizzling in the opposite part, and if you turn your back at the direction of sun
rays, a spectrum of colour appears like a bow, and if we look at the rainbow from a high enough
building or from a low flying aircraft, the bow is actually a circle, that's
because thousands of tiny spherical drops of H2O acts like prisms.
Ray of sunlight enters the tiny sphere of H2O near its top surface,
dispersed and reflected into the water-sphere according to their frequencies,
violet being deviated the most and red the least, and on reaching the opposite
side of the water-sphere (convex and concave), colours of light partly refracted
out into the air and partly reflected back into the lower surface of the sphere,
this cycle of refraction and dispersion continues.
The angle of red light disperse at 42o and the angle of violet
light disperse at 40o, drops of water-sphere when look from another
angle forms other peoples rainbow in bow shape because the ground's in the way.
A double rainbow results from double reflection (and extra refraction loss),
thus the
secondary bow is much dimmer.
Light travels at a slightly lower speed in air than @ at the speed of C
(300,000 kilometres per second in a vacuum), and at about 3/4
(three-fourths) the speed in water, in other word -- different speeds in
different materials due to the process of refraction.
The cause of refraction is the change in the average speed of light going from one medium to another. Just how much differ in speed is given by the index of refraction of a
material. n is the ratio of the speed of light in a vacuum to the speed
of light in a material, for example:
speed of light in vacuum
n = ---------------------------
speed of light in material
The speed of light in water is (4/3) of C, so n =
1.33
The angle of incidence is larger than the angle of refraction depends on the relative speeds of light in air and in water. Perhaps it's
wise to train a seal as lifeguard to save swimmers in distress, seals swim
faster than human ever could take on a straight line path of least-time in
water.
The Critical Angles
The critical angle of light in water is app. 48o, an experiment we can all
do at home with a tub of water and a water-proofed torch. If you fill the bath
tub full of water and submerge the torch light at the bottom, tipping the light
slowly from left to right, you will notice the intensity of the light beam
diminishes at certain angle, these beam reduces to zero when it tends to graze
at the surface of the water. And when the beam of light tipped beyond a
critical point (48o), all the light is reflected back into the tub.
The light striking the air-water surface obeys the law of reflection and
total internal reflection rules -- the angle of incidence is equal to the angle
of reflection, the only light emerging from the water surface is
diffusely reflected from the bottom of the bathtub.
Thus a diver looking up (the fisheye view) sees a 180o outside
world (but with a limited light view of apr.96o), this horizon
to horizon is seen through the critical points of 48o twice (96o).
And the incident angles greater than 48o is internally
reflected, no light will escape beyond the angle of 96o.
Where's a mirror reflects 90% of incident light back, a prism reflect almost
100% (little lost of reflection speed) of the incident light at a 45o
slanted face was the principal reason to use prisms for optical instruments.
A prism changes the direction of the light beam by 90o twice (180o)
then turns the image upside down means a pair of prisms can be used to lengthen
the light path, and re-inverts the image in a binocular.
The smallest critical angled substance (apart from fiber-optic) turns out to
be diamond @ app. 24.5o though slightly differ in diamond-colours.
Once light enters a diamond gemstone, most of the incident light reflects back
internally at an angle greater then 24.5o gives a great dispersion as
light exits through the many facets, hence, we see unexpected flash of a wide
array of colours and sparkles.
The rule of reflection also apply to light-pipe (optical fiber) which pipes
the light through a series of total internal reflections, such like a bullet
rebounding along the inner wall twists and turns in the pipe. Optical fiber are
use in many decorative displays as well as in communications, and surgeons use
them to inspect internal organs of patients.
Optical fiber is immune to temperature changes or magnetic field fluctuations unlike
electric wires, also much less likely temper by eavesdroppers.
Author
31/12/2008
Mantra: You can't cure brain death but you can prevent
it.
What's the moral in these stories?
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