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

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

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

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

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

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

ELECTROMAGNETIC SPECTRUM 740nm 370nm

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

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 (?)

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

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!

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!

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.

() 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

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

Energy of the EM Spectrum

Energy of the EM Spectrum Low Energy High Energy

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