1. The Electromagnetic Spectrum

2. Light is a Type of Energy
A type of radiant energy you can see
It travels in waves
The range of colours that make up visible light is called the visible spectrum
There are other types of radiant energy that exist but we just cannot detect with our eyes

3. Waves
Amplitude
Time

4. Key Parts of a Wave
Crest: The farthest point above the resting position
Trough: The farthest point below the resting position
Wavelength: The distance between two consecutive crests/troughs
Amplitude: The height of a crest/trough; shows how much energy is involved
Frequency: The number of cycles a wave passes through in a given amount of time. Hertz (Hz) = number of cycles in 1 second

5. Waves with Different Amplitude

6. Waves with Different Frequencies

7. Waves of Visible Light
Each natural colour that makes up white light travels at different frequencies/speed
Prisms slow down light, and each colour gets slowed down by a different amount
That’s why each colour bend at a slightly different angle

8. Other Radiant Energies

9. Radio Waves Waves are about 1km long Uses: Ship/boat communication
AM/FM radio stations
Cellphones TV
Ongoing research about effects on human brain

10. Microwaves One wave can fit into 1cm Uses Microwave ovens
Satellite communication

11. Infrared Radiation (IR)
Above 1000 waves can fit into 1cm
Can be detected by skin as heat
Emitted by living things and warm objects
Uses
Thermal photographs
Remote controls

12. Visible Light Up to 500,000 waves can fit into 1cm
Red: longest wavelength, travels slowest, lowest energy
Violet: shortest wavelength, travels fastest, highest energy
Uses
Artificial light
Lasers

13. Ultraviolet Radiation (UV)
1 million waves can fit in 1 cm
Can be detected by skin and special treatments
Can cause sunburns, skin cancer, and cataracts in the eye
Uses:
Suntanning
Fluorescent lights
“Black lights”

14. X-Rays 100 million waves can fit into 1 cm
Can pass through skins, but not bones
Can damage body cells
Uses:
Medical imaging
Airport security

15. Gamma Rays 10 billion waves can fit into 1 cm
Dangerous energy given off by radioactive materials
Can break DNA molecules
Uses:
Scientific studies
Cancer treatment (some)