Dispersion of light and uses of the Electromagnetic Spectrum

1. Spectra
Reflection of light :
Refraction of light :
Diffraction of light :
The change in direction of light when striking
a material without going through it.
The change in direction of light when going
from one material to another.
When a wave spreads out as it travels through
a gap or past the edge of an object.

2. Red
Orange
Yellow
Green
Blue
Indigo
Violet
Dispersion of light :
When different wavelengths refract
with different angles.

4. Why are some colours
of light more strongly refracted than others?
λ

6. Questions
2.- a) Which has a longer wavelength, red light or violet light?
b) Which one has the greater frequency?
c) Which one will get refracted the most?
1.- a) What colours are there in the white light spectrum?
b) What is wavelength?
c) What is frequency
3.- a) Which travels faster in vacuum, violet light or red light?
b) Which travel faster in glass?
c) What is the speed of light in vacuum?

7. Visible Light

8. The Elecromagnetic Spectrum
Increasing Frequency
Increasing Wavelength
Increasing Energy
v = f λ
3x10^8 m/s

9. The E.M. Spectrum:Uses

10. Radio Waves
Low Energy Part
Infrared
Micro Waves
Visible Light (Red, Orange, Yellow, Green, Blue, Indigo, Violet)
Low Energy Part mostly used in Communications

11. Low Energy Part
Radio Waves Longest wavelength; lowest frequency
TV and Radio Broadcasting
Short distances
Longdistances
Why long wavelengths used in longer distances?
They can reflect (not passing through) the Ionosphere

12. Low Energy Part
Micro Waves Shorter wavelength than Radio waves
Higher frequency than radio waves
Satellite TV ; Mobile Phone signal; Cooking
Although Microwaves, they are not the same frequency nor wavelength
As used in mobile phones

13. Low Energy Part
Infrared Remote controls for sending signals, Security alarms, Cooking

14. Low Energy Part
Visible Light In optical fibers i.e. internet – data transmission,
Eyesight

15. Ultraviolet light
Ionizing radiation
Gamma Rays
X - rays
High Energy Part
Ionize = remove an electron from a atom, molecule or substance

16. High Energy Part
Ultraviolet light Fluorescent lamps, verify money forgery, tanning

17. High Energy Part
X - rays Medical equipment (Bone imaging)
Crystallography, airport security

18. High Energy Part
Gamma Rays Medical equipment (radio therapy)
sterilization

20. 1.- a) Complete the graph above with the missing waves from the E.M Spectrum.
b) Put accordingly the following words.
High Energy Part Low Energy Part Long Wavelength Short Wavelength
High Frequency Low Frequency
2.- Name two uses for each of the waves in the E.M. Spectrum

21. Whiteboard 1