why are there only 7 colours in a RAINBOW ??

Answer 1

the 7 colour rainbow story was just made up, both to simplify things, and because 7 is a symbolic number. One clear sign of this is that indigo is not that clearly identifiable from violet, much less so than, for example, turquoise or topaze are identifiable from "pure" green and blue.

in reality, a rainbow exhibits a continuum of all possible colours in the visible spectrum.

so you could just as well say that a rainbow has 10 colours, or 30, or 50, or 100, or 10'000, or a million.


hope this helps

Answer 2

The rainbow effect can be observed whenever there are water drops in the air and sunlight shining from behind the observer at a low altitude or angle. The most spectacular rainbow displays when half of the sky is still dark with draining clouds and the observer is at a spot with clear sky overhead. The rainbow effect is also commonly seen near waterfalls or fountains. Rainbow fringes can sometimes be seen at the edges of backlit clouds and as vertical bands in distant rain or virga. The effect can also be artificially created by dispersing water droplets into the air during a sunny day.

In a very few cases, a moonbow, or night-time rainbow, can be seen on strongly moonlit nights. As human visual perception for colour in low light is poor, moonbows are most often perceived to be white.

The rainbow's appearance is caused by dispersion of sunlight as it is refracted by (approximately spherical) raindrops. The light is first refracted as it enters the surface of the raindrop, reflected off the back of the drop, and again refracted as it leaves the drop. The overall effect is that the incoming light is reflected back over a wide range of angles, with the most intense light at an angle of about 40°–42°. This angle is independent of the size of the drop, but does depend on its refractive index. As seawater has a higher refractive index than rain water, the radius of a 'rain'bow in a sea spray is smaller than a true rainbow. This is visible to the naked eye by a misalignment of these bows [1].

Since the water is dispersive, the amount that the sunlight is bent depends upon the wavelength, and hence colour, of the light's constituent parts. Blue light is refracted at a greater angle than red light, but because the area of the back of the droplet has a focal point inside the droplet, the spectrum crosses itself, and therefore the red light appears higher in the sky, and forms the outer colour of the rainbow. Contrary to popular belief, the light at the back of the raindrop does not undergo total internal reflection; however, light that emerges from the back of the raindrop does not create a rainbow between the observer and the Sun. The spectra emitted from the back of the raindrop do not have a maximum of intensity, as the other visible rainbows do, and thus the colours blend together and do not form a rainbow.

A rainbow does not actually exist at a location in the sky, but rather is an optical phenomenon whose apparent position depends on the observer's location. All raindrops refract and reflect the sunlight in the same way, but only the light from some raindrops reaches the observer's eye. These raindrops are perceived to constitute the rainbow by that observer. The position of a rainbow in the sky is always in the opposite direction of the Sun with respect to the observer, and the interior is always slightly brighter than the exterior. The bow is centred on the shadow of the observer's head, or more exactly at the antisolar point (which is below the horizon during the daytime), appearing at an angle of approximately 40°–42° to the line between the observer's head and its shadow. As a result, if the Sun is higher than 42°, then the rainbow is below the horizon and cannot be seen as there are usually not enough raindrops between the horizon (that is: eye height) and the ground, to contribute. One exception is when the observer is at the top of a mountain or a similar vantage point, for example an aeroplane (see below). Another exception occurs when the rainbow is produced by a garden sprinkler. Although in this case to get sufficient drops they must be very small, resulting in a quite colourless bow.

It is difficult to photograph the complete arc of a rainbow, which would require an angle of view of 84°. For a 35 mm camera, a lens with a focal length of 19 mm or less would be required, whilst most photographers are only likely to have a 28 mm wide-angle lens. From an aeroplane, one has the opportunity to see the whole circle of the rainbow, with the plane's shadow in the centre. This phenomenon can be confused with the glory, but a glory is usually much smaller, covering only 5°–20°, as opposed to over 80° for a full circle rainbow.

You could get more information from the link below...

Answer 3

There isn't.

Strictly speaking there are an unlimited number of different hues in the visible spectrum between infrared and ultraviolet. Look at a rainbow and it's a blur of colours from red to violet, not a set of seven stripes.

As some of the colours have names, like red and orange, then it's sensible to use them. You'd be there for ever if you said 'red, slightly less red with a hint of orange, a bit more orange than the last one,' and so on...

Answer 4

isn't 7 colours enough? there is probably 7 because got wanted there to be 7 because there are 7 days in a week just like god wanted

Answer 5

There are way more than 7. 7 is only a broad catagory. Where those main colours mix, other colours are created, only you just cant see them.

Answer 6

The colours actually blend into each other, so there are really many more than 7, we just say 7 because it is easy.

Answer 7

Because all colours can be made by mixing them, they are the primary colours. Why do you need anymore ?

Trust a woman god just painted the sky, now she wants a different colour....!

Answer 8

Visible spectrum, there are colours of rainbow r o y g b i v, violet you back time, red on other hand you go forward. Black, all these mixed. As well as wavelength, elements,?( I don`t understand as of yet) Absortion: you need go the wavelengths.

Answer 9

7 main colours - although really a full spectrum of visable colours to the naked eye. In theory there are more colours if onlt we could see them!

Answer 10

You see 7? I see 8!