Purple, yellow, red and green,
The King cannot reach it, or the Queen;
Nor can old Noll, whose power's so great:
Tell me this riddle while I count eight.
Remember this old nursery rhyme? Probably not. And I will save your time when you try to Google its answer for, it’s simply a rainbow. However I don’t want to test your brains, I would rather tell you about colors. But first we begin we will talk about light.
Light can be defined as waves; normally we say light waves, meaning light as waves. But it has another properties of behaving like an electromagnetic wave and particle. Sounds absurd yeah, light as a particle. But it’s true, sorry to hurt your feelings if you thought light is only an electromagnetic waves, or simply to put, waves. Let’s now define waves and particle.
Waves have wavelength and amplitude and some motion they are going through. This property defines colors. Putting colors again on hold for some time. Since light has wavelength and a motion, it’s like radio waves only difference is that you can’t see radio waves but you can see light, not there waves of course.
Don’t argue you can see the radio.
These waves are of order ranging between 380 nanometers to about 740 nm, nanometer is a billionth of meter, which comes down to a millionth of a millimeter. Now you can imagine why you can’t see a wave. Anyway. So light as we found, is like waves. As it has wavelength and a frequency ranging between 405 THz to 790 THz. However we can see from 390-750. Your next question might be what happens to the rest of light? Yes it is there but we can’t see them as our eyes doesn’t have capacity to see all that wavelength. But you probably heard of infra red and ultra violet rays. Those are beyond our vision but they are present all around us, a common example would be microwaves which we use to cook food.
And this is the range where we can see light and different colors. No we are not yet to colors.
After defining and giving enough proof that light is electromagnetic wave. Lets look other side which tells us light is also a particle.
To put in simple, very simple terms, if light was waves and it has infra red and microwave, these infra red and microwaves are said to have radiation effect. I mean, microwaves are type of radiation right? And same goes with infrared. So what I want to say is that, it is an electromagnetic radiation.
I can explain this in simple way by telling you this that light bounces of objects. If light was wave, It should had passed through mirror, or objects, but instead it bounces back, or reflects back. This property is only explained by particles. It means light is also a particle. Light follows the famous duality theory of Newton, which was later verified by Einstein’s quantum theories. According to duality theorem light will act as wave or particle depending upon the condition it is considered for, for example if light passes through a prism, it will act as waves and all those waves will get refracted (deviated) and we get a nice colorful spectrum. But when same light is falling on objects or mirror to be stern, it will reflect showing the properties of a particle.
Particle property can be only understood at quantum level. As it is hard to understand light’s particle property at normal scale what we face at day to day life, nor I would explain this now as we almost deviated from topic.
But if we are to talk about colors, then we will stick to wave property of light. As I gave example that when light is passed through a prism it will refract and will break up into 7 colors namely and in order of, VIBGYOR
Violet, Indigo, Blue, Green, Yellow, Orange and Red.
All these colors are different only because of their wavelengths.
color
|
wavelength interval
|
frequency interval
|
~ 700–635 nm
|
~ 430–480 THz
| |
~ 635–590 nm
|
~ 480–510 THz
| |
~ 590–560 nm
|
~ 510–540 THz
| |
~ 560–490 nm
|
~ 540–610 THz
| |
~ 490–450 nm
|
~ 610–670 THz
| |
~ 450–400 nm
|
~ 670–750 THz
|
So when you see red color you see actually a wave with wavelength ranging between 700-635nm and frequency ranging between 430THz-480THz
When all these colors combine they form white light. The process when light is passed through a prism is the process where one can learn about the numbers of colors and fair idea of frequency of those colors.
The longer the wavelength the straighter the wave will go and that is why red is on top and violet is at bottom.
So where a rainbow does comes from? Is there a big huge giant prim in sky which refracts light and a rainbow is formed. Answer is obviously no. many things refract light, for e.g. water, when you put a straw in glass or spoon in glass it appears broken at the point of immersion. This is due to same fact that light had bend when it entered into water. So this means things are main culprit and which bend light. But what makes them culprit? It’s their density. When light enters from one medium to another due to difference in density light changes its path. Prism was made up of glass and had density higher than air so it bends and when it leaves prism it again bends. While leaving prism due to many different frequency and wavelength modules inside, it splits and all wavelengths become separate, similar thing happens with rainbow, but here water droplets acts as a prism. Since water has different density that air (duh!) so light will again refract when going into water, but colors will deflect further when leaving water droplet. Imagine what a million of water droplet will do; yes they will create a rainbow. Beautiful beautiful rainbow.
So to conclude everything, light consists of colors, many different colors, we see 7 basic, and combining all these we see white light.
