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 Light The 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

740nm370nm

Wavelength: 1m to m Frequency: 3 x 10 9 to 3 x 10 4 Hz Uses: Telecommunications, TV, Radio Dangers: none

Wavelength: 0.001m to 1m Frequency: 3 x to 3 x 10 9 Hz Uses: Telecommunications, RADAR, Cooking Dangers: can produce burns, cataracts, cancer (?)

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

Wavelength: 370nm (violet) to 740nm (red) Frequency: 8 x to 4 x 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: m to 370nm Frequency: 3 x to 8 x Hz Uses: discos, tanning salons, counterfeit detections, pollination Dangers: skin cancer Bees see in UV to help them find pollen!

Wavelength: to m Frequency: 3 x to 3 x 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: to m Frequency: 3 x to 3 x 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