# How the white ray of light changes to a spectrum of colours

1. Jun 26, 2004

### gunblaze

Hi....Juz curious.

I was doing the prism experiment yesterday and was just curious about how the white ray of light changes to a spectrum of colours...

Has it got anything to do with the change in the speed of the different colours of light, the frequency / the wavelength? Or just purely the refraction that causes the change?

I will appreciate any replies...Thx

2. Jun 27, 2004

### kuenmao

You're more or less right.
Different colours of light have different frequencies. Different frequencies, because of the same speed, means different wavelengths. That causes different speeds in different mediums, if you don't count vacuum. Hence, the velocity ratio is different, and so the refraction gives different angles for different colours. Red light, with the lowest frequency and longest wavelength among visible light, bends the least.

3. Jul 7, 2004

### gunblaze

thx for that//...

so u mean that when light travels into the prism, it's speed will change, therefore changing its wavelength and frequencies thus resulting in the refraction of the white light to different colours?

4. Jul 7, 2004

### Kurdt

Staff Emeritus
White light consists of all the colours. When it is put into a prism the refractive index for each individual wavelegth is different. Thus all wavelengths diffract at different angles and cause the spectrum pattern you observe. There is no actual change in the frequency and wavelength of the colours. The speed difference is due to the photons being absorbed by the glas molecules and emitted again. The time it takes to emit is what causes the apparent change in speed.