1. Pink Floyd: Dark side of the Moon
Is this correct?

2. Dispersion Red Orange Yellow Green Blue Indigo Violet
When white light is split into the colours of the spectrum / rainbow
ROYGBIV
Red
Orange
Yellow
Green
Blue
Indigo
Violet

3. PhET Bending light applet
Change refractive index, n to see how wave bends
~ compare with light…

4. Why does white light split into the colours of the spectrum?
Refraction index (n) depends on
colour wavelength ()

6. Why does white light split into the colours of the spectrum?
Index of refraction (n) depends on
colour wavelength ()
Red: longest  lowest n
Violet: shortest  highest n
bends the most

7. Rainbows are a result of dispersion

8. The Rainbow
A ray of light strikes a drop of water in the atmosphere
It undergoes both reflection and refraction
First refraction at the front of the drop
Violet light will deviate the most
Red light will deviate the least
Each colour is slowed down by a different amount and so refracts at a slightly different angle.

10. The many raindrops contribute to the rainbow that we see.

11. If a raindrop high in the sky is observed, the red ray is seen
A drop lower in the sky would direct violet light to the observer
The other colors of the spectra lie in between the red and the violet

13. Frequently, a dim secondary rainbow is seen outside the primary bow
Frequently, a dim secondary rainbow is seen outside the primary bow. Secondary rainbows are caused by a double reflection of sunlight inside the raindrops, and appear at an angle of 50°–53°. As a result of the second reflection, the colours of a secondary rainbow are inverted compared to the primary bow, with blue on the outside and red on the inside. The secondary rainbow is fainter than the primary because more light escapes from two reflections compared to one and because the rainbow itself is spread over a greater area of the sky.

14. Key words: total internal reflection, refraction, spectrum.
NZQA
This prism ornament consists of two hollow glass pentagonal (5-sided) prisms joined together and filled with water. It is hung where the sun can shine on it and reflects light sending out a spectrum: the colours of the rainbow.
This diagram shows a cross section of one of the prisms with a light ray, accurately drawn, entering one face and leaving another. The glass sides are so thin that they can be neglected, so that the light ray can be considered to be passing directly from air to water.
water 1 2 3
air
white light ray
Discuss what happens to the light ray at each of the points 1, 2 and 3 in the diagram. Include the following key words in your answer.
Key words: total internal reflection, refraction, spectrum.

15. M
water
water 1 2 3
air
white light ray
Discuss what happens to the light ray at each of the points 1, 2 and 3 in the diagram.
Include the following key words in your answer
total internal reflection, refraction, spectrum.
At point 1 white light enters the water and refracts with no noticeable dispersion, i.e. one cannot see any of the colours of the spectrum in the water.
At point two there is total internal reflection of the white light.
At point 3 the colours refract depending on their wavelength showing the rainbow spectrum.