1. Convection
Dispersion

2. Learning Objectives
You should learn :
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.

3. Here is a glass prism:
A ray of white light arrives

4. away from or towards the normal the normal
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.

5. devi ated In fact, the ray is : (bent through an angle), and
dispersed (split up into separate colours)
like this.

6. Red is deviated most / least ? least
screen
What happens now?
Red is deviated most / least ?
least
Violet is deviated most / least ?
most

7. There is a spectrum on the screen:V
screen
There is a spectrum on the screen:
Red Orange Yellow Green Blue Indigo Violet
ROY G BIV

8. What is the real difference between red and violet light ?4
10 000 mm
wavelength
violet
red 7
10 000 mm

9. Learning Outcomes
You should now:
Understand what happens when white light enters a prism,
Distinguish between deviation and dispersion,
Know the colours of the spectrum, in order,
Understand the connection between colour and wavelength.

10. If you are connected to the web at the moment, click below to see what’s available:

11. Definition of Dispersion
Dispersion is the separation of white light into a spectrum by the process of refraction.

12. Dispersion with a prism
Violet is deviated the most
Red is deviated the least
Prism showing light dispersion for different colours - Explore Science
Prism & Dispersion - Great Barr School
Dispersion - Crocodile Clip Presentation
web site:

13. The spectrum of white light
The numbers are the wavelengths
of the colours in nanometres
where 1 nanometre = m.
Sequential Puzzle on Colour Spectrum order- by KT
web site:

14. The cause of dispersion
Dispersion occurs because different colours of light travel at slightly different speeds through transparent substances.
In glass, perspex and water red travels quickest, violet slowest.

15. An example of dispersion caused by water
Convection
The rainbow
An example of dispersion caused by water

16. Question 1
Choose appropriate words to fill the gaps in the paragraph below:
____________ occurs when white light is split up into a ____________ by the process of refraction.
In glass violet light travels more __________ than the other colours and so is deviated the _________.
The spectrum consists of red, ________, __________, _________, ________, indigo and _________.
A __________ is formed when water causes dispersion.

17. Question 2
Explain why
orange light is deviated less than blue light in a prism,
we know that indigo light travels slower than green light through water,
there are seven colours in the spectrum list.

18. Simulations
Prism showing light dispersion for different colours - Explore Science
Prism & Dispersion - Great Barr School
Dispersion - Crocodile Clip Presentation
Sequential Puzzle on Colour Spectrum order- by KT  - Microsoft WORD version
Prism - multishape prism and single light ray - no extra reflections - netfirms
Prism - non dispersive reflections and refractions - NTNU

19. Convection Crossword – by KT
Puzzles
Convection Crossword – by KT

20. Related Presentaions Refraction Powerpoint by KT
Colour Powerpoint by KT