A ray of white light enters a glass prism and is refracted. Different colors of light are refracted by different angles, dispersing the white light into a visible spectrum on the screen. Violet light is refracted at the greatest angle and red light at the smallest angle, producing the rainbow of colors from red to violet in order of the letters in ROYGBIV. When sunlight passes through raindrops, the water droplets act as prisms and disperse the light into a rainbow through refraction.
6. • How a light ray is deviated by a prism,
• How white light is dispersed by a prism,
• The colours of a white light spectrum,
• About the wavelengths of different
colours.
7. Here is a
glass prism:
A ray of white light
arrives
8. What happens to the ray of
light?
It is (mainly) reflected or refracted
? away from or towards
the normal the normal
But different colours are refracted by
different angles.
9. In fact, the ray is :
• (bent through an angle), and
• dispersed (split up into separate
colours)
like this.
10. What happens now?
R
V
screen
Red is deviated most / least ?
least
most
Violet is deviated most / least ?
11. R
V
screen
There is a spectrum
on the screen:
Red Orange Yellow Green Blue Indigo Violet
ROY G BIV
12.
13.
14. Perhaps the most spectacular and best known
atmospheric optical phenomenon is the rainbow.
Sunlight and water droplets are necessary for the
formation of a rainbow.
Furthermore, the observer must be between the Sun
and rain.
When a rainbow forms, the water droplets act as
prisms and refraction disperses the sunlight into the
spectrum of colors, a process called dispersion.
The curved shape of the rainbow results because
the rainbow rays always travel toward the observer
at an angle between 40 and 42° from the path of
the sunlight.
