1. Starter Who can tell me what these numbers represents?
Can you go the other way?

2. ELECTROMAGNETIC SPECTRUM
4th March 2014
ELECTROMAGNETIC SPECTRUM
Lesson Objectives
By the end of this lesson, you will be able to:
State that the electromagnetic spectrum consists of transverse waves only
Describe the different types of wave that make-up the electromagnetic spectrum
Explain the uses and dangers associated with the electromagnetic spectrum

3. Question... What are the two main classifications of waves?
And what can you tell me about them?
A wave transfers energy through a medium without the medium itself having to move.
The energy is transferred by disturbances (oscillations) in the medium (material) through which the transfer is occurring.
There are many different kinds of waves
Electromagnetic waves pass through a vacuum & do not need to be carried by a substance.
Light, infra red & microwaves all make things warm up. X-rays & gamma rays can cause ionisation and damage to cells, which also show that they carry energy.
Loud sounds make things vibrate or move. Even the quietest sound move your eardrum
Waves on the sea can toss big boats around and can generate electricity.
Waves also transfer information, as well as energy. E.g. TV, radio, speech, fibre optics etc 3

4. Transverse Longitudinal
BEFORE WE START...
What are the two main classifications of waves?
Transverse
Longitudinal
A wave transfers energy through a medium without the medium itself having to move.
The energy is transferred by disturbances (oscillations) in the medium (material) through which the transfer is occurring.
There are many different kinds of waves
Electromagnetic waves pass through a vacuum & do not need to be carried by a substance.
Light, infra red & microwaves all make things warm up. X-rays & gamma rays can cause ionisation and damage to cells, which also show that they carry energy.
Loud sounds make things vibrate or move. Even the quietest sound move your eardrum
Waves on the sea can toss big boats around and can generate electricity.
Waves also transfer information, as well as energy. E.g. TV, radio, speech, fibre optics etc
eg Light
eg Sound
Both involve vibrations
Both transport energy
Neither transport matter 4

5. ELECTROMAGNETIC SPECTRUM
All electromagnetic waves:
Are ___________ waves
Can travel through a __________ (space)
Travel at the ____________

6. ELECTROMAGNETIC SPECTRUM
All electromagnetic waves:
Are transverse waves
Can travel through a vacuum (space)
Travel at the speed of light
~300,000,000 m/s = 3.0 × 10 (?) m/s

7. ELECTROMAGNETIC SPECTRUM
740nm
370nm

8. RADIOWAVES Wavelength: 1m to 100000m Frequency: 3 x 109 to 3 x 104 Hz
Uses: Telecommunications, TV, Radio
Dangers: none

9. MICROWAVES Wavelength: 0.001m to 1m Frequency: 3 x 1012 to 3 x 109 Hz
Uses: Telecommunications, RADAR, Cooking
Dangers: can produce burns, cataracts, cancer (?)

10. INFRA-RED Wavelength: 740nm to 0.01m
Frequency: 4 x 1014 to 3 x 1011 Hz
Uses: Heating, cooking, TV remotes, night-vision
Dangers: can burn

11. VISIBLE LIGHT Wavelength: 370nm (violet) to 740nm (red)
Frequency: 8 x 1014 to 4 x 1014 Hz
Uses: seeing
Dangers: eye damage from bright lights
Visible light is best at getting through our atmosphere – which is why we use it to see!

12. Bees see in UV to help them find pollen!
ULTRAVIOLET
Wavelength: 10-9 m to 370nm
Frequency: 3 x 1017 to 8 x 1014 Hz
Uses: discos, tanning salons, counterfeit detections, pollination
Dangers: skin cancer
Bees see in UV to help them find pollen!

13. X-RAYS Wavelength: 10-12 to 10-7 m Frequency: 3 x 1020 to 3 x 1015 Hz
Uses: medical imagery, security
Dangers: cancer
Hand with Rings by Wilhelm Röntgen.
The first "medical" X-ray of his wife's hand taken on 22 December 1895.

14. () GAMMA RAYS Wavelength: 10-16 to 10-9 m
Frequency: 3 x 1024 to 3 x 1017 Hz
Uses: cancer treatment, observing the universe
Dangers: cancer

15. The Dangers of the EM Spectrum
As the wavelength of EM spectrum changes, the way the different wavelengths interact with matter also changes.
As the frequency increases, wavelength gets smaller. Eventually the waves are so small that they can interact with cells, DNA and atoms. This is called IONISING RADIATION.
NON-IONISING
IONISING

16. Energy of the EM Spectrum

17. Energy of the EM Spectrum
Low Energy
High Energy

18. Lesson Objectives By the end of this lesson, you will be able to:
State that the electromagnetic spectrum consists of transverse waves only
Describe the different types of wave that make-up the electromagnetic spectrum
Explain the uses and dangers associated with the electromagnetic spectrum