BC Science Connections 8 - Topic 3.1 Notes PDF

BC Science Connections 8 UNIT 3 Energy can be transferred as both a particle and a wave TOPIC 3.1 How does electromagnetic radiation shape your world?  Topic 3.1: How does electromagnetic radiation shape your world? Electromagnetic radiation is a form of e...

BC Science Connections 8 UNIT 3 Energy can be transferred as both a particle and a wave TOPIC 3.1 How does electromagnetic radiation shape your world?  Topic 3.1: How does electromagnetic radiation shape your world? 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 of are harmful, and other Images of the Sun taken with types are essential to telescopes that detect a different survival of life on type of electromagnetic radiation. (Clockwise, from top left: infrared, Earth x-ray, ultraviolet, optical) Concept 1: Electromagnetic radiation is an important part of your world. Seven different types of electromagnetic radiation: – Radio wave – Microwave – Infrared – Visible light – Ultraviolet – X-ray – Gamma-ray Image of the Sun taken with an ultraviolet telescope. 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. 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. Figure 3.1: Electromagnetic radiation is often discussed online and covered by the news.  Wavelengths Longer than Visible Light Radio Waves Radio waves have the longest wavelength and lowest energy and frequency compared to all other types of electromagnetic radiation. MRI technology uses radio waves to see inside our body. MRI scan of the brain See pages 154 - 155 (c) McGraw Hill Ryerson 2007  Wavelengths Longer than Visible Light Microwaves Microwaves have the shortest wavelength and highest frequency of all the radio waves. – Microwaves are used in: cooking food, and telecommunications. Radar uses short wavelength microwaves. A radar image of the Earth’s surface – Radar is used in: tracking the motion of objects, weather forecasting, and taking images of the Earth’s surface. See pages 155 - 156 (c) McGraw Hill Ryerson 2007  Wavelengths Longer than Visible Light Infrared Waves Electromagnetic radiation that has a wavelength longer than red light but shorter than that of radio waves. Infrared radiation is also referred to as heat. – Infrared waves are used in: remote controls, infrared cameras, and CD-ROM readers. Infrared cameras record differences in temperature. See page 157 (c) McGraw Hill Ryerson 2007  Wavelengths Shorter than Visible Light Wavelengths shorter than visible light have more energy than visible light. Ultraviolet Waves Ultraviolet waves (UV) are just beyond the visible region of the spectrum. This radiation possesses much more energy than visible light. – UV waves striking your skin allows Wearing sunglasses and sunscreen help protect you your body to make Vitamin D. against harmful UV radiation. – Overexposure to UV can cause sunburns and possible skin cancer. See pages 158 - 159 (c) McGraw Hill Ryerson 2007  Wavelengths Shorter than Visible Light X rays X rays have a much shorter wavelength and higher energy and frequency than ultraviolet waves. – X rays are commonly used to photograph teeth and bones. – X rays are also used to detect small cracks in metals and also to photograph the inside of machines. See pages 159 - 160 (c) McGraw Hill Ryerson 2007  Wavelengths Shorter than Visible Light Gamma Rays Gamma rays are the shortest wavelength and highest energy and frequency of the electromagnetic spectrum. Gamma rays result from nuclear reactions. Gamma rays can be used in radiation therapy to kill cancer cells. Gamma rays can be used to kill cancer cells. See page 160 Take the Section 4.3 (c) McGraw Hill Quiz Ryerson 2007  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?  Concept 2: Sources of electromagnetic radiation are all around you. Many different sources of electromagnetic radiation: Some sources are artificial (cell phones, light bulbs) Some sources are The Sun is a source of all living organisms types of electromagnetic (humans) radiation.  The Sun: A Source of All Types of Electromagnetic Radiation Energy carried by radiation is produced by nuclear fusion Hydrogen nuclei collide and combine to form helium Fusion of 1 g of hydrogen atoms: reaction releases 65 billion kJ of energy (50 000 The large pieces of pizza!) amount of energy released 500 trillion grams of by the Sun hydrogen fuse in the Sun supports life on Earth. every second  Chemical Reactions in Living Organisms: A Source of Visible Light Some reactions occur in living organisms Female anglerfish have a lure that gives off visible light to attract prey Bacteria in the lure produce the light Female anglerfish have a lure that gives off visible light  Heated Materials: A Source of Visible Light and Infrared Radiation All objects, including you, give off infrared radiation. As objects get hotter: give off more infrared radiation (sensed as heat) If objects are very hot: give off visible Light bulbs give off infrared light and infrared radiation and visible light. radiation When the bulb is turned on, the wire inside gets very hot and gives off light.  Telecommunications: A Source of Microwaves and Radio Waves Cell phones are a source of microwaves. Microwaves carry information from the cell phone to nearby cell phone tower Cell phone towers create microwaves that carry the Cell phone towers create information to another microwaves that carry cell phone information from cell phone to cell phone.  Telecommunications: A Source of Microwaves and Radio Waves Communication systems (fire, police, emergency systems) and radio stations generation radio waves Send signals to radio receivers that convert them into sound  X-ray Tubes: A Source of X-rays X-rays are produced are produced in an x- ray tube. High-speed electrons are released from a heated tungsten wire Electrons collide with metal surface that stops them The sudden change in speed of the electrons generates x-rays X-rays are produced in x-ray tubes. X-rays can be used to create images of teeth and bones.  Radioisotopes: A Source of Gamma Rays Gamma rays are produced by unstable nuclei of certain atoms. Atoms with unstable nuclei are called radioisotopes. Radioisotopes have too much energy A gamma camera image of a thyroid gland To become stable, they injected with radioactive iodine. The brighter area give off energy in different has taken up more iodine, so the camera forms, including gamma detects more gamma rays. rays  Radioisotopes: A Source of Gamma Rays Iodine-131 is a radioisotope that gives off gamma rays Used to treat thyroid cancer When a patient swallows it, it will go to the thyroid A gamma camera image of a gland to kill the thyroid gland injected with radioactive iodine cancer cells  Discussion Questions What type or types of electromagnetic radiation are given of by the following sources? a) a halogen light bulb b) the Sun c) iodine-131 d) you  Discussion Questions Identify three sources of electromagnetic radiation that you interacted with this week. A type of starfish uses electromagnetic radiation to warn predators that it does not taste good. What type of electromagnetic radiation is most likely given off by the starfish?  Concept 3: Electromagnetic radiation enhances how we sense our world. 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  Solving Crimes Electromagnetic radiation helps uncover evidence. Luminol: – Used to find blood – Undergoes a reaction with iron in blood to give off Figure 2.3: Luminol is visible light sprayed at a crime scene to test for blood.  Solving Crimes Infrared photography: Senses temperature differences Used to find hidden evidence (weapons) within walls X-ray, infrared, ultraviolet radiation: Used to uncover art forgeries Figure 2.3: Luminol is by identifying varnishes, sprayed at a pigments, brushstrokes crime scene to test for blood.  Diagnosing Disease Electromagnetic radiation is used to identify medical problems. Magnetic resonance imaging (MRI) Radio waves and magnets work together Figure 2.4: This MRI image shows a cross- Signals are used to section of a human create an image of abdomen. It has been tissues coloured to help show the different organs.  Diagnosing Disease X-ray imaging: Used to diagnose broken bones and cavities in teeth X-rays are absorbed by bones and teeth, but pass through most other body tissues X-ray of bones  Diagnosing Disease Blue light cancer detection: B.C. Cancer Agency developed a device that shines blue light into the mouth to detect cancer Under blue light or ultraviolet radiation: – Normal tongue will glow Cancerous tissue will look dark  Seeing Earth from Space Satellites use different types of electromagnetic radiation to gather information about Earth (remote sensing). Weather satellites: Use visible light and infrared radiation from Earth to monitor weather conditions Can detect movement of clouds and amount of Figure 3.5: Satellite image moisture in atmosphere of Earth  Seeing Earth from Space LANDSAT satellite: Measures visible light and infrared radiation from Earth’s land surface to map it Helps with monitoring and observing land use (examples: loss of Figure 3.5: Satellite image rainforests, finding of Earth near-shore shipwrecks)  Viewing the Universe Electromagnetic radiation is being used to study the universe. Hubble Space Telescope: Uses mirrors to collect and focus visible light Figure 3.6: This image of a supernova (exploding Other instruments on star) combines data from the telescope sense telescopes sensing different kinds of ultraviolet and infrared electromagnetic radiation. radiation  Viewing the Universe Very Large Array radio telescope: Largest radio telescope on Earth 27 receivers work together to sense radio wave radiation Figure 3.6: This image of from space a supernova (exploding star) combines data from telescopes sensing different kinds of electromagnetic radiation.  Discussion Questions Describe how you are an electromagnetic radiation detector.  Summary: How does electromagnetic radiation shape your world? Electromagnetic radiation is an important part of your world. Sources of electromagnetic radiation are all around you. Electromagnetic radiation enhances how we sense our world.