Nature Of Light

Refraction - The Nature Of Light

The nature of light is such that it bends when passing from one transparent medium to another.

Identifying one medium from another is by the differences in their densities.

An example would be a ray of light passing through a block of glass as shown in diagram 01.

Glass has a density different from air and thus air and glass are two different mediums.

When a ray of light hits a block of glass or another medium at right angles, it will pass right through without any deviation at all.

However if the ray enters the block of glass at an angle, it does change its direction as it enters the glass medium. It actually bends towards an imaginary line called the "normal".

This particular behaviour of light is called refraction.

The Normal

The "normal" is at right angles to the surface of the medium, and passes through the point at which the ray of light comes into contact with the medium.

It is necessary to imagine the existence of this line for the purpose of relating something to the angle with which the ray of light hits the surface of that particular medium.

I have drawn diagrams using MS Paint which I believe would help to understand the idea.



Diagram 01

As shown in diagram 01, R1 is ray of light entering the block of glass which is shaded blue. R2 is the refracted ray, where i is the angle of incidence and r is angle of refraction.

When this angle of incidence is divided by the angle of refraction, the value thus obtained is known as the refractive index of the substance in which the ray of light undergoes refraction.

This value is represented by the greek letter "µ." The refractive index of a substance is shown by the formula µ=i/r.


Total Internal Reflection
Total Internal Reflection

Total Internal Reflection - Nature Of Light

Since glass is denser than air, a ray of light entering a glass block bends towards the normal.

Conversely, a ray of light originating from a point inside the glass block will bend away from the normal when it exits.

The angle at which the ray of light hits the surface in relation to the normal is known as the angle of incidence.

The angle in relation to the normal after refraction is called the angle of refraction.

When the angle of incidence is divided by the angle of refraction, a value is obtained.

This value is referred to as the refractive index of the substance through which the light is passed.

The higher the refractive index the greater the ability of the substance to bend light.

The ability of glass to cause light to bend is what enables optical instruments to function.

A ray of light originating from within a dense medium, when emerging into a less dense medium, tends to move away from the normal.

Irrespective of whether the ray of light bends towards or away from the normal, which in turn is determined by where the beam of light originates, the deviation is always referred to as refraction.

As shown in diagram 02, if the angle of incidence keeps on increasing, at one point the "emerging" ray will be along the surface which separates the two mediums.

When this occurs, the angle of refraction will be ninety degrees. That means the angle between the normal and the emerging ray will be a right angle.

It is at this point that the angle of incident gets callled the critical angle. From this moment the refractive index of the other medium no longer needs be considered.

If the angle of incidence is further increased, beyond the critical angle, the light actually begins to reflect off the separating surface.


Diagram 02

Referring diagram 02 C, B and A are rays of light originating within the block of glass which is shaded yellow. The beam C, represented by a blue line, undergoes deviation and moves away from the normal on emerging from glass to air.

The beam B represented by a red line deviates in proportion to the angle of incidence. The angle of incidence is always relative to the direction of the light beam. The deviation that the red beam undergoes is such that it grazes the surface which separates the two mediums.

The beam of light A, represented by the green line hits the separating surface at an angle which is sufficient to cause TOTAL INTERNAL REFLECTION. Examining the diagram will make things clear.

Optical Fiber Technology

Optical fiber technology works on the principle of total internal reflection.

An optical fiber cable is somewhat similar to a current carrying wire.

The only difference being the metal cord within the insulated wire is replaced by a substance that enables light to pass through.

An optical fiber resembles a current carrying wire, is flexible and permits light to travel through it just like a pipe allows water to flow from one end of it to the other.

The light that is transmitted from one end of the optical fiber to the other does not undergo any signal loss as all the light that is transmitted via the fiber is kept within the cable itself.

This of course is due to total internal reflection.

Total internal reflection is what enables the continuity of the flow of light even when the cable undergoes bending.

No energy is lost as the light is contained within the cable.


The Colors Of The Rainbow
The Colors Of The Rainbow


Materials which allow light to pass through are called transparent.

Some substances allow light to pass through but causes diffusion such that nothing could be viewed through it. An example would be frosted glass.

Substances that block light and do not allow it to pass through are called opaque.

So you need to remember the terms transparent, translucent, and opaque.

The Spectrum - Nature Of Light

Quite apart from this, white light, or light from the sun is actually made up of several colors.

A color could be described as light of a particular frequency.

An example could be found when comparing a red beam of light to a blue beam of light. The red beam is of a different frequency than a blue beam.

Likewise each color is identified by a frequency typical of its own.

It also happens that a red ray of light will undergo a deviation different to that of a blue ray of light when it passes from one medium to another.

The angle of refraction of a red beam of light will be different to the angle of refraction of a blue beam of light. Each color has its own angle of deviation.

Sir Isaac Newton performed an experiment in which he passed a ray of sunlight through a glass prism.

The different colors which make up the white light, each of them vibrating at different frequencies, deviated at different angles and emerged revealing the true identity of each color.

As shown in diagram 03, when passed through a glass prism, the beam of white light split into the primary colors that white light is made of.

Since the color red deviates most and blue the least, it was found that when a screen was placed on the other side of the prism to capture the colors, red was found at the very bottom, and blue, the least deviating of the colors, at the top, the other colors occupied the middle range in an order typical of their respective frequencies.

Visible Light

The Electromagnetic Spectrum - Nature Of Light

This experiment performed by Sir Isaac Newton also proved that white light is made up of seven primary colors, namely violet, indigo, blue, green, yellow, orange and red.

These are the colors of the rainbow. This combination of colors is known as the visible spectrum.

Further proof comes along by replacing the screen with an inverted prism.

The inverted prism causes the colors entering it to converge back to form a beam of pure white light.

An extremely important thing to note here is that the human brain is tuned to identify only colors which have a frequency range that matches red and blue and all the other colors in-between. There are other "colors" that we really cannot see.

These are beyond the extremes occupied by red and blue on the visible spectrum.

Refraction Via A Prism

Light - A Form Of Energy

Light is a form of energy and can be generated by altering the orbital patterns of electrons in atoms.

Intense heat can cause this to happen. For example the filament in an incandescent light bulb offers resistance to the flow of electrical current through it.

This resistance generates heat and the heat in turn is what generates light.

The process involved in causing the filament to get hot enough to generate white light is known as heating a substance to incandescence.

Most importantly this needs to be done in the absence of air, otherwise the filament or the substance involved will "burn out."

Nearing Black Holes

Experiments have shown that light also has a tendency to bend when in the vicinity of strong gravitational or magnetic fields.

Scientists have discovered that certain areas in space in which high gravitational fields exist, appear totally black.

This is because all the light in the vicinity have been "sucked" in towards the source of the gravitational fields.

Therefore these areas appear to be dark patches in space. They are also known as black holes. More about them later!

Answer This Survey Please

Was this article useful to you in any way?

  • Oh yes, it was indeed, explained in plain English too. The diagrams were quite clear as well. Thanks.
  • It explains some basics that most of us need to be reminded of. Thanks.
  • Who? Me? Well, which article?
See results without voting

For Your Entertainment - The Speed Of Light

The Basics Of Light

Check out my previous essay on light. Right here I discuss the very basics of light.

I explain in brief what eclipses are, and how they occur.

I discuss some basic aspects concerning the speed of light, and I also explain what a light year really is.

Check out the very basics of light right here!

Summary On The Nature Of Light

Light bends when passing from one medium to another. If the medium which it is entering is denser than the medium in which it originated, the ray of light bends towards the normal.

The normal is an imaginary line which is at right angles to the surface which separates the two mediums, and passes through the same point at which the ray of light hits the surface of the second medium. This deviation is called refraction of light.

Total internal reflection is caused when the refraction of light exceeds a certain limit.

The limiting factor occurs when the angle of incident exceeds what is known as the critical angle. The critical angle is dependant on the density of the medium concerned.

It is beyond this limiting point that light reflects from the border that separates the two mediums, bouncing back within the medium in which it originates.

Optical fiber technology relies on both refraction as well as reflection of light and cannot function if one does not transform into the other.

White light is made up of the colors that are identified in the rainbow. Passing white light through a glass prism will cause the white light to split into the colors of the rainbow which would be visible on a screen.

If the screen is replaced by an inverted prism, these colors would converge back into a beam of white light.

Visible light is generated when something is heated to incandescence. An example would be an incandescent light bulb in which the filament is heated in the absence of air, by passing an electric current through it.

Light is sensitive to strong gravitational fields and has been known to bend towards sources which generate intense gravity.

Black holes in space are known to display very strong gravitational fields and any light originating in the vicinity of black holes is sucked into them.

Black holes do not allow light or any other electromagnetic waves to travel past them. They are sucked in.

Light waves are also electromagnet waves and are similar to radio waves, micro waves, and x-rays.

Light, does not need a medium to travel in. Just like radio waves and x-rays light can travel in the absence of air.

So ... such is the nature of light! I shall attempt to explain black holes in another article. Stay tuned!

... concluded


Science Fiction From The Same Author

The Lighter Side Of It All!

© 2009 quicksand

More by this Author

  • About Feng Shui - My Experiences

    This article is all about Feng Shui and is a true story based on my very own experiences. Although not an exacting science, the concept of Feng Shui is actually based on the assumption that a form of energy called Chi...

  • The Future Of The English Language

    The importance of the English language needs be stressed at this moment as there is a serious threat lurking around. Online chat and SMS texting have scarred the English Language to a noticeable degree. The future of...

  • My Review On Reiki

    Although it is another form of therapy, Reiki is different. Reiki is of Japanese origin, and does not involve massage or yoga. It is believed that a form of controllable energy is involved in the healing process, and...

Comments 53 comments

Paraglider profile image

Paraglider 7 years ago from Kyle, Scotland

Nice hub, QS. Newton's work on light was also away ahead of his time. He was talking about the 'corpuscular nature' of light long before there was any knowledge of photons. (I've got a black holes hub too, but it's not quite what you'd imagine!)

quicksand profile image

quicksand 7 years ago Author

I guess it was the 'corpuscular nature' theory that was the prelude to the thought that light is made up of photons. Thanks for commenting, Paraglider. :)

Tatjana-Mihaela profile image

Tatjana-Mihaela 7 years ago from Zadar, CROATIA

Hi, Quicksand,

Thumbs up for this article, and thanks for reminding me on rainbow on this raining day in Croatia.

quicksand profile image

quicksand 7 years ago Author

Hi Tanja,

Hope you get sunshine once again soon. Thanks for visiting my hub.

Shalini Kagal profile image

Shalini Kagal 7 years ago from India

I've always been fascinated by light - thanks for that informative hub quicksand!

quicksand profile image

quicksand 7 years ago Author

Thanks Shalini, for the interest shown in my essay on light. It is even more fascinating when you get to know that the speed of light is the maximum attainable speed ... however, when something is caused to accelerate (if it is possible) such that it reaches the speed of light after a predetermined period of time, then, on reaching that speed, that "something" ceases to exist ... in this realm!

Shalini Kagal profile image

Shalini Kagal 7 years ago from India

Isn't just the thought amazing? Transmigration could explain so many unexplained phenomena, couldn't it?

btw, great new avatar :)

quicksand profile image

quicksand 7 years ago Author

Transmigration is probably the transfer of a soul to another body. The fiction write Lobsang Rampa spoke about it in all his books. He claims to have been a Lama in a monastery in Tibet. When his time was up, he says that by the process of transmigration, his soul commenced occupying the body of a Canadian whose picture adorned the sleeve of all his books. He was a fiction writer, remember?

The disappearance of matter when its velocity approaches the speed of light suggests that it commences existence in another dimension in another time. If you've got time, check out the book "The Universe And Dr Einstein" By Bertrand Russel, and follow it up with "A Brief History Of Time" by Steven Hawking.

As for my new avatar, that was the five year old Quicksand. It was during this era that I first taw a puddytat!

Thank you very much for your visit and your comments, Shalini ... I appreciate it very much! :) :) :)

Shalini Kagal profile image

Shalini Kagal 7 years ago from India

Yes, I love all Lopsang Rampa's books! I was thinking however, more of the Clestine Prophecy and the tranmigration of the soul by vibrating to a speed greater than light which makes one move into another dimension.

Ahhhh - Tweety? nice :)

quicksand profile image

quicksand 7 years ago Author

According to the accepted theories, matter ceases to exist when it reaches the speed of light. This gives rise to a lot of speculation, generating some ridiculous theories too. Connecting to transmigration, although I cannot directly do so, I guess transmigration is not simply replacing the void created by a departing soul with another soul. I guess ... well, I dare not guess! :)

dipless profile image

dipless 7 years ago from Manchester

True but we will never accelerate a particle with mass to C, due to the loretnez contractions and time dilations. Thus altering their perspective of space time and never allowing them to quite reach the speed of light.

quicksand profile image

quicksand 7 years ago Author

Thanks dipless, for this comment.

However I remember an equation according to which the mass of a particle tends to infinity when V approaches C, thus making it physically impossible to reach C as an increase in mass causes a corresponding "resitance" to acceleration.


Lgali profile image

Lgali 7 years ago

QS -Nice hub

dipless profile image

dipless 7 years ago from Manchester

Mass does not increase as it approaches the speed of light. The interpretation is a reflection of errors in Einstein's Relativity Theory.

Consider the cyclotron the force is said to be f=qvxB = mv^2/R and the radial frequency is: qvB=mv^2/R which gives qvB/m=w the radial frequency.

In practice the cyclotron frequency is different w= qB/m sqrt(1 -(v/c)^) this led to the conclusion that Einstein's mass increase was real m=m0/sqrt(1-(v/c)^2).

The real answer is that the mathematics is wrong. f=qvxB= qvBsin(x)= mv^2/R thus

w= (qvB/m) sin(x).

where sin(x) = sqrt(1 -(v/c)^2).

Einstein's and Lorentz Relativity Factors Beta=v/c and Gamma= 1/sqrt(1 -(v/c)^2) are in reality the manifestation of Conservation of Energy and Equilibrium. Beta is the Redshift z=v/c=cos(x) and Gamma is 1/sin(x).

Simply put, the Total force F=qvB = -qv.B + qvxB = -qvBcos(x) + T qvBsin(x) where T is the unit vector transverse to the radial direction. Cos(x) =v/c reflects the radial component of force. This radial component is ignored in physics and sometimes claimed to be impossible. If v and B are not perpendicular, there is a scalar f=-qvBcos(x). Cos)x)= v/c is the Redshift of Hubble's measure and of the Quantum redshift and Fine Structure Constant.

Einstein's Relativity Theory needs revision, mass does not increase as it approaches the speed of light, the formula is incomplete and the Lorentz Factors are the fix and have been mis-interpreted. As the mass approaches the speed of light the cosine approaches z=v/c=cos(x)=1 and the sin(x) approaches zero so qvxB=qvBsin(x) goes to zero and qvBsin(x) = mwv gives w=(qB/m)sin(x) goes to zero not because of increased mass but because of the sin(x) going to zero as the angle goes to zero.

The scalar force -qvBcos(x) is a vibration force in parallel to the field. This is assumed to be impossible, e.g. no force parallel to the magnetic field. This is another mis-interpretation. Maxwell claimed that light was an electromagnetic field on the basis of the relationship E=cB or B=E/c. Thus if qv.E is real qv.B=qv.E/c = q(v/c).E is real.

quicksand profile image

quicksand 7 years ago Author

Dipless, thanks for this valuable contribution. The impression that M tends to infinity when V tends to C is supportive of the thought that C is specifically designed for electromagnetic waves. What you have stated now throws new light on certain theories generated by observing black holes. Thanks once more! :)

dipless profile image

dipless 7 years ago from Manchester

No worries, physics is kind of a passion for me! :) Just a bit more food for thought

Some textbooks say that the mass of an object increases along with its speed. In doing so, they typically introduce the concept of relativistic mass mREL given by:

Adopting this line of thinking, it's natural to ask where the extra mass comes. Do objects somehow acquire more atoms as they go faster and faster? Or does each individual atom increase its mass?

The standard, generally accepted reply to the introduction of the concept of mREL is to say that while it's possible to introduce such a notion and so talk about mass increasing with velocity, it's preferable not to do so for a variety of reasons. Many of these are somewhat technical but one of them is as follows: introducing the notion of mREL makes the relativistic generalization of Newton's second law F=ma very messy. In particular, it forces you to say that all objects actually have two masses: one associated with forces parallel to the direction of motion y3m0 and a second linked to the forces perpendicular to the direction of motion ym0.


As a result of such complications, it's generally accepted that the mass of an object is the mass it has when at rest. That is, its rest mass m0. This quantity is independent of the speed of the object and so most physicists accept that the mass of an object remains constant at m0 no matter how fast it's going. The only thing that changes is that the object acquires more kinetic energy as it gathers speed.


In fact, Einstein himself once wrote It is not good to introduce the concept of the mass as M= ym = 1/(1-v2/c2)1/2m of a body for which no clear definition can be given. It is better to introduce no other mass than the rest masses.


While the above is not incorrect, it's typically frowned upon as it centres on the problematic notion of mREL.

To begin this alternate answer, let's think about Einstein's famous equation E=mc2. It says that mass can be converted into energy and vice-versa. It also can be viewed as suggesting that, at a fundamental level, mass and energy are one. That is, they're both part of the single property we might call mass-energy.

According to this stance, when we increase an object's energy by, say, exerting a force on it, we also necessarily increase its mass. So, the answer to the question Where does the mass come from? is that it comes from the energy we put into an object to increase its speed.

Let's look at an example. Imagine a hockey puck lying at rest on ice. To get it moving, we need to give it energy. We could do this by, for instance, hitting it with our stick in a process that converts chemical potential energy within our muscles into kinetic energy of the puck. 

As mass is fundamentally equivalent to energy, it could be said that we've also given the puck extra mass. That is, its relativistic mass has increased from m0c2 to ym0c2. The underlying cause of this increase is simply the fact that we've given the puck more energy.

To see this mathematically, note that beginning with the equation ETOTAL = mREL c2 = KE + m0c2, we can obtain mREL(v) = KE(v)/c2 + m0. From the second equation, it's clear that v dependence of mREL is due solely to the fact that KE is a function of v. That is, the increase in the relativistic mass of an object stems from its increased kinetic energy.

We should note, however, that as the hockey puck speeds up it does not somehow magically acquire more and more atoms.

In essence, in this way of thinking about things, we've redefined mass so that increasing the energy of an object necessarily raises its mass.

To deal with the final part of the question How is mass defined?, in this context we can think of the rest mass m0 as being a measure of the energy content of an object. If an object has rest mass m0 then, in principle, we can extract an amount of energy E=m0 c2 from it.

p.s. sorry wouldn't copy the sub and super scripts :(

quicksand profile image

quicksand 7 years ago Author

The way I had previously understood is that mass ceases to obey the accepted laws of motion, I mean the Newtonian laws after it reached 90% the speed of light. It is at this speed, I used to believe that mass commences to increase.

However as YOU pointed out, if mass does increase, then additional protons or neutrons "materialize" from somewhere. This, of course is impossible since matter cannot be created.

Since this "resistance to motion" which is somewhat an unexplainable thing, increases logarithmically after V passes 90% of the speed of light, such that exactly at the point where V=C, M reaches infinity. On the path to reaching infinity, the illusion of snowballing mass is created.

Thanks once again Dipless, I appreciate all the trouble you have taken.

BTW, I guess sub scripts and super scripts don't work in the comments area. Perhaps they do in the main text area.

soni2006 profile image

soni2006 7 years ago from New Delhi, India

A very nice hub indeed. A very good title and good amount of keywords.

quicksand profile image

quicksand 7 years ago Author

Hi Raj, thanks for your visit and your remarks. :)

GeneralHowitzer profile image

GeneralHowitzer 7 years ago from Land of Salt, Philippines

wow nice hub hehehe i teach your article to my students, i never thought it would be very interesting to write article about electronics, im'an ece qs... thanks for the info..

quicksand profile image

quicksand 7 years ago Author

Hi General, I am glad you found it interesting. Thanks for dropping by. :)

Manna in the wild profile image

Manna in the wild 7 years ago from Australia

@dipless who stated:

"Mass does not increase as it approaches the speed of light. The interpretation is a reflection of errors in Einstein's Relativity Theory."

SR is a pillar of modern physics and is one of the best tested theories around. To read the above is unsettling and, quite frankly, puts into question all of your comments. How do you possibly justify such a statement?

Hi. @quicksand: You did a pretty good hub. Here are a couple of constructive comments...

White light is not made up of seven distinct colours. It contains a spectrum of colours. See for details.

“Experiments have shown that light also has a tendency to bend when in the vicinity of strong gravitational or magnetic fields.” Almost. The main gripe I have with this statement is that light is affected by any strength of gravity – and it is a certainty, not a tendency. Of course the effect is noticeable near strong magnetic fields.

That colourful prism picture has a white band in the middle. Why?

“An optical fiber cable is somewhat similar to a current carrying wire.” No it's not. It's really different. Rather than me try to repeat this, just take a squiz at but read critically.

quicksand profile image

quicksand 7 years ago Author

Hi Manna in the wild!

Okay, I'll make the corrections right here!

"White light is made up of seven visible colors plus "colors" that are beyond the comprehension of the human eye."

"An optical fiber is similar to a wire carrying signals."

Thanks for your visit, and I appreciate your constructive comments too! :)

dipless profile image

dipless 6 years ago from Manchester

@manna the wild, please don't get me wrong, SR is the framework from which certain branches of modern physics are built.

Please understand that all i admit that in SR it "appears" to an observer that an object is increacing in mass, however this is only due to the frame of reference.

soumyasrajan 6 years ago from Mumbai India and often in USA

A very informative and well written article quicksand! Even if you are a scientist and think about these things or hear talks on much more complicated ideas often, it is pleasure to go through articles like the one you have written and then discussions in comments. Some times it helps one to understand even better.

But I wonder why you left out things like dual nature of photon (particle wave duality) , Heisenberg uncertainty, principle (you can never measure both velocity and mass accurately at the same time etc.) Max Planck's black body absorption experiments with which sort of whole theory of physics crumbled at a time when people had started feeling they are in right direction and may now be able to explain every thing and led Einstein to formulate his theories etc. They explain today's style of understanding light and physics (quantum theory) and are indeed amazing.

It is fascinating to see with your eyes that nature of light seem to be what you want it to be. If you think of it as bunch of particles it looks like that and if you think of it as a wave it looks that!

This is one of the greatest understanding of 20th century and is not just for Physics but many other aspects of our lives.

These ideas are not so difficult to understand and explain as many might feel. At the same time they have eternal enjoyment.

A good initial reference

soumyasrajan 6 years ago from Mumbai India and often in USA

one more comment for you and Shalini. I wonder whether it is a good idea to try to explain faster than light phenomena or transmigration with these theories. I think in these theories (Einstein's relativity theory etc.) one considers essentially it as an axiom that no mass or information travels faster than light.

This is not exactly the same as saying that nothing travels faster than light in this world. What you are saying is that I am going to study only that part of world where objects do not move faster than light.

Of course that does not desist Physicist from dwelling into particles which travel faster than light (Tachyons).

Quantum Physics does study such objects but more as unstable phenomena. If some day there is enough experimentally verifiable evidence of stable tachyons, a lot of current ideas may crumble as happened in the last century with Max Planck's simple experiments and current theories may have to be expanded/ modified.

quicksand profile image

quicksand 6 years ago Author

Thanks once again Mr Soumyasrajan.

The theories involving tachyons are most confusing as some even attribute the inability to "see" them due to the fact that they travel faster than light. This also gives rise to a suggestion that tachyons should assume the characteristic of being able to reflect or generate their own "light"! Light, should then defy the Doppler effect!!!

Manna in the wild profile image

Manna in the wild 5 years ago from Australia

Bear in mind that a tachyon is a theoretical consequence of relativity. There are no experiments involving tachyons. These are a result of mathematical time symmetries in the equations. It is not inconceivable that relativity will be absorbed by an updated theory in the future just as Newton's theories are contained by relativity. This could result in either supporting the real world existence of tachyons or removing their possibility from theoretical physics.

Regarding a mass 'becoming massless' at the speed of light, this is not really a practical interpretation of the theory. A massless particle (i.e. something with no rest-mass) can ONLY go at c. Something with any mass at all can never go at c. And finally, following on from the first statement, a massless particle travels at c in ALL frames of reference.

So something with any mass at all could be ridden like a vehicle. A brain contained within that vehicle would experience all massless particles moving at c, and time would appear to pass normally. All other experiences (those in other inertial frames) would still see massless particles at c, and the brain's vehicle at some speed slower than c and apparently with a slower clock than experienced by the brain we spoke of. (Imagine a clock face moving away from you at extreme speed, each 'tick' would take longer than a local second.)

- I also noted that you said fiber optics pass light without loss. This is not correct because there are several mechanisms which degrade the light from one end to another: decoherence, multi-path, leakage etc.

- "An optical fiber resembles a current carrying wire," Well, not really. A copper wire permits an electromagnetic field (essentially photons!) to be disturbed to carry information and power from one end of the cable to the other while the electrons recombine and bounce about and create heat and drift along at amazingly slow speed.

In contrast, an optical fiber permits photons to travel near c from one end to the other in a contained path (ultimately longer than the cable) because it is a wave-guide. The two mechanisms are different.

quicksand profile image

quicksand 5 years ago Author

Thanks Manna, I thought the "insulation" prevented leakage in an optical fiber, and the path restriction prevented incoherence.

Manna in the wild profile image

Manna in the wild 5 years ago from Australia

The insulation is primarily to protect the fiber physically. The light is contained within the fiber by the refractive index wrt radius. You may bend the waveguide a little but too much will create a corner too tight for the light to be refracted internally and some will leak out. This is a way to tap into an optical fiber without breaking it.

Decoherence happens due to impurities and this is most significant for systems trying to send entangled photons. The imputities cause a distubance which breaks entanglement. This is what limits the distance of quantum key encryption. (Same problem in air)

quicksand profile image

quicksand 5 years ago Author

Oh, I never considered "impurities" within an optical fiber, as optical fibers have been compared to the superconducters of electrical impulses, supporting theories that the efficiency of an optical fiber will not vary with temperature unlike in wires carrying elecrical signals. Although I am not sure about the conductivity of an optical fiber being affected by temperature. Maybe there is some new light concerning these theories?

Manna in the wild profile image

Manna in the wild 5 years ago from Australia

Well it's true that electrical conductors and semiconductors are severely affected by heat. Some increase resistance with temperature, and some decrease. Some more than others. Glass (and plastic) fiber is more stable with respect to temperature.

There is a reasonably fair comparison but a little confusing my opinion between a glass fiber carrying light, and a superconductor carrying electrons.

Resistance in a conductor is caused by collisions of electrons. This produces heat and wastes energy as a result. In a superconductor the resistance of the conductor reduces to zero. Unfortunately this happens at very low temperatures and it's costly to do. There is much research to try and create room-temperature superconductivity and if achieved it will cause a technological revolution.

quicksand profile image

quicksand 5 years ago Author

Looks like what appears as "complete transparency" to the unaided eye is not really sans impurities.

Manna in the wild profile image

Manna in the wild 5 years ago from Australia

That's so true quicksand. All of engineering is a compromise!

quicksand profile image

quicksand 5 years ago Author

Thanks a lot Manna, for adding some valuable info. :)

topquark profile image

topquark 5 years ago from UK

Nice article. Would be great for students trying to learn about reflection and refraction.

quicksand profile image

quicksand 5 years ago Author

Thanks TopQuark, you've got some great new hubs!

Parking Lot Lighting 5 years ago

that a good idea about Total Internal Reflection ~!

thank you for share!

Parking Lot Lighting

soumyasrajan 5 years ago from Mumbai India and often in USA

I cam back to your hub after several months. Enjoyed your exchange with Manna in wild very much. Learnt a few things better. I like his description "That's so true quicksand. All of engineering is a compromise!"

quicksand profile image

quicksand 5 years ago Author

Hello Mr Soumyasrajan! Sure Manna is a very bright guy.

Welcome back and thanks for commenting. :)

Camerondiaz 5 years ago

i surely liked all of this. thanks alot you guys for adding such info !! :)

bingo lines 5 years ago

can i ask ? ahm.what makes up light? :))

quicksand profile image

quicksand 5 years ago Author

BingoLines, I hope to add that bit later on. Thanks for your visit. Cheers 2U!

selena gomez 4 years ago

can i ask some ques abt the reflection of light

quicksand profile image

quicksand 4 years ago Author

Sure you can. I'll do my best to answer them. :)

Olde Cashmere profile image

Olde Cashmere 4 years ago from Michigan, United States

The science of light has always been a major interest of mine. Reading this hub was fun and full of information explained in a clear way. Very well done quicksand. Voted up, useful, interesting, and awesome :)

quicksand profile image

quicksand 4 years ago Author

Thanks for visiting my hub, Olde Cashmere, and thanks for your votes and your kind words too. :)

metchie 4 years ago

im so nervouse

quicksand profile image

quicksand 4 years ago Author

Don't be!

arpit 3 years ago

if a prism divides the light into 7 colours and if an another prism is kept inverted than what will happen i need this answer really urgently

quicksand profile image

quicksand 3 years ago Author

Then the colors converge back to produce a beam of white light.

secretone 2 years ago

hello quicksand thanks for being an author of this hub I'd learn more in this website

quicksand profile image

quicksand 2 years ago Author

Hi SecretOne, thanks for your kind words. :)

    Sign in or sign up and post using a HubPages Network account.

    0 of 8192 characters used
    Post Comment

    No HTML is allowed in comments, but URLs will be hyperlinked. Comments are not for promoting your articles or other sites.

    Click to Rate This Article