10.1 Light and the Electromagnetic spectrum

What is Light? A form of energy It is a range of electromagnetic radiation (a wave pattern made of electric and magnetic fields that can travel through empty space) that can be detected by the human eye Is energy that moves in a wave-like motion

Waves A distrubance that transfers energy from one point to another without transfering matter Structure of a wave CREST – highest part of the wave TROUGH- lowest part of the wave REST POSITION - the level a which there are no waves CREST TROUGH REST POSITION

Properties of Waves Wavelength – distance from crest to crest or trough to trough Amplitude – height of the wave from rest position Frequency – the rate of repitition of the wave - measured in cycles/second (Hertz) amplitude

How much energy is carried? -the amount of energy transferred by a wave depends on amplitude and frequency The higher the frequency, the shorter the wavelength and the more energy

Electromagnetic Spectrum Invisible light-like waves + visible light Microwaves

Electromagnetic Spectrum Microwaves Violet Indigo Blue Green Yellow Orange Red

Properties of Light 1. It travels in straight lines 2. It moves rapidly - around 300,000 kilometres per second. At this speed it can go around the world 8 times in one second. Laser

3. It travels faster than sound Ex. We see lightning first and then we hear thunder

Uses of Electromagnetic waves Radio waves – longest wavelength -radio and TV signals, cellphones, satellite communications for the internet, MRI machines Microwaves – heat food, radar, map the earth and space objects

Infrared Waves – felt as heat, alarms (motion sensors), night vision goggles Ultraviolet Rays – produced by sun and stars, burns skin and increases risk of skin cancer, disinfect water, DNA analysis X- rays – penetrate human tissue for medical imaging, luggage scanning, photographing the inside of pipelines/engines to check for fractures Gamma Rays – penetrate human tissue, sterlize medical equipment, kill cancer cells, produced by black holes, neutron stars

Homework p. 383 #1 Make a chart listing all the electromagnetic wave. Use p to list the uses of each