3.1 Electromagnetic Radiation Name:____________ Date:_____________ Block:_____
This MRI image shows a cross section of a human abdomen. Question What technologies do you know uses invisible waves? Write down at least 5 answers. This MRI image shows a cross section of a human abdomen.
Intro to EM Radiation: https://science.nasa.gov/ems/01_intro
Electromagnetic Radiation Electromagnetic radiation is a form of energy. Given off by different sources on Earth and in the universe Most comes from the Sun Some types are harmful, and other types are essential to survival of life on Earth
Electromagnetic Radiation Seven different types of electromagnetic radiation: Radio wave Microwave Infrared Visible light Ultraviolet X-ray Gamma-ray Radio waves – radio broadcasts Microwaves – cooking, mobile and satellite communications, WiFi Infrared – heat radiation – everything emits infrared. Remote controls, heaters, infrared goggles Visible - light that allows humans to see UV – sterilization, banks to detect counterfeit money, tanning beds - too much exposure leads to skin cancer X-rays – to see internal structures Gamma – produced by energy changes in nuclei of atoms. New use in cancer cells… Image of the Sun taken with an ultraviolet telescope.
Think of a Mnemonic R ___________________________ V ___________________________ U ___________________________ X ___________________________ G ___________________________
Electromagnetic Spectrum The range from longest wavelength to shortest wavelength is called the Electromagnetic Spectrum High Energy Low Energy
Electromagnetic Spectrum
Sources of Electromagnetic Radiation There are many different sources of electromagnetic radiation: Some sources are artificial such as cell phones, light bulbs Some sources are from living organisms such as humans The Sun gives off all types of electromagnetic radiation. The large amount of energy released by the Sun supports life on Earth. The Sun is a source of all types of electromagnetic radiation.
Nuclear Fusion https://www.youtube.com/watch?v=W1ZQ4JBv3-Y
Electromagnetic radiation enhances how we sense our world. Luminol is sprayed at a crime scene to test for blood When luminol mixes with iron, it emits visible light You are an electromagnetic radiation detector. Skin: special cells sense infrared radiation, and send a message to your brain that is interpreted as heat Eyes: sense visible light to see brightness, objects, and colour Electromagnetic radiation and technology lets us “see” in a new way This image of a supernova (exploding star) combines data from telescopes sensing different kinds of electromagnetic radiation
Figure 3.1: Electromagnetic radiation is often discussed online and covered by the news.
Figure 3.1: Electromagnetic radiation is often discussed online and covered by the news.
Blue Light https://www.youtube.com/watch?v=3tjeS0updfI
Figure 3.1: Electromagnetic radiation is often discussed online and covered by the news.
X Rays https://www.youtube.com/watch?v=gsV7SJDDCY4
Discussion Questions Why do you think sunglasses have special lenses that filter out ultraviolet light? Why might you want to limit the amount of time you spend in front of an electronic screen at night? 1. Since ultraviolet radiation can cause eye damage, it makes sense for sunglasses to have special lenses to filter out the radiation. 2. Blue light given off by electronic screens has been linked to sleep problems.
Electromagnetic Spectrum
Radio Waves Has the longest wavelength and lowest energy Communication systems (fire, police, emergency systems) and radio stations generate radio waves They send signals to radio receivers that convert them into sound Used in MRI’s
Microwaves Cell phones are a source of microwaves. Microwaves carry information from the cell phone to nearby cell phone tower Microwave ovens use microwaves Cell phone towers create microwaves that carry information from cell phone to cell phone.
Infrared Radiation All objects, including you, give off infrared radiation. Referred to as heat radiation As objects get hotter, they give off more infrared radiation that is sensed as heat Used every day in remote controls, by computers to read CDs and DVDs, heaters, infrared goggles
Visible Light Visible light is a wave that we can see The visible spectrum includes seven colours: ROY G BIV Do you remember the colours? red, orange, yellow, green, blue, indigo, violet Together these 7 colors are known as the visible spectrum. Each color emitted have different wavelengths Some chemical reactions give off visible light.
Visible Light Of the waves that make up visible light, red has the longest wavelength and lowest energy. Violet has the shortest wavelength and highest energy.
Ultraviolet Coming from the sun, ultraviolet rays strike your skin and enable it to make vitamin D Often used for sterilization Solving crimes Tanning beds Overexposure can cause sunburns and skin cancer
X-Rays X-rays are produced in an x-ray tube and can be used to create images of teeth and bones Overexposure can be dangerous
Gamma Rays Gamma rays are produced by unstable nuclei of certain atoms. Atoms with unstable nuclei are called radioisotopes. Radioisotopes have too much energy To become stable, they give off energy in different forms, including gamma rays Gamma rays are highest in energy and have the shortest wavelengths Focused burst of gamma rays are used in radiation therapy to kill cancer cells
Radioisotopes: A Source of Gamma Rays Iodine-131 is a radioisotope that gives off gamma rays It is used to treat thyroid cancer When a patient swallows it, it will go to the thyroid gland to kill the cancer cells A gamma camera image of a thyroid gland injected with radioactive iodine
Discussion Questions a halogen light bulb the Sun iodine-131 you What type or types of electromagnetic radiation are given of by the following sources? a halogen light bulb the Sun iodine-131 you