Starter. The Electromagnetic Spectrum Learning Objectives I must be able to state that all electromagnetic waves are transverse. I should be able to.

Starter

The Electromagnetic Spectrum

Learning Objectives• I must be able to state that all

electromagnetic waves are transverse.

• I should be able to describe the electromagnetic spectrum.

• I might be able to explain differences n wavelength and frequencies of waves within the electromagnetic spectrum.

P1.7 Infrared, visible and ultraviolet

The Tarantula Nebula photographed by the Hubble Space Telescope in visible light, infrared and ultraviolet.

Invisible LightThe Electromagnetic Spectrum

Electromagnetic Spectrum• Visible light, infrared, ultraviolet radiation

are all types of electromagnetic radiation.• The waves transfer energy from one place

to another and can travel through a vacuum.

• Electromagnetic vibrations travel at right angles to the direction of energy transferred by waves. They are therefore transverse waves.

The Electromagnetic Spectrum

Wavelength and Frequency• Electromagnetic waves that have

long wavelengths have short frequencies.

• And electromagnetic waves that have short wavelengths have long frequencies.

Task 2

•Complete worksheet 1.7b.

Electromagnetic Spectrum• A full range of electromagnetic

waves is called the electromagnetic spectrum.• It is like a bigger version of the visible

spectrum that includes wavelengths of light that we cannot see.

Task 3

• Complete worksheet 1.7c.

Can you think of an easy way to remember…

From the shortest wavelength to the longest.• Gamma rays• X-rays• Ultraviolet rays• Visible light• Infrared• Microwaves• Radio waves

740nm 370nm

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

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

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

• 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!

• 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!

• 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.

• 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.

IONISINGNON-IONISING