Trapped in a Newtonian Universe • Though Newton’s Apple and Calculus are helpful, his theories are only as good as the next round of evidence. • Now we have electromagnetic fields and energy without tiny solid particles. • The Newtonian Universe is most popular and helpful for the everyday understanding of how the world works, but our popular view is a few centuries behind the science at work.
What is Light? • James Clerk Maxwell theorized that electromagnetic waves were disturbances in electromagnetic fields. • A magnetic field can be created by a change in the electric field. • The disturbance in the electromagnetic field is called an electromagnetic wave that does not need a physical medium to propagate through and, as Maxwell’s math predicted, has a speed of about 300,000 km/s, which is the known speed of light.
An electromagnetic wave A disturbance in an electro magnetic field where a change in a magnetic field creates a change in an electric field that carries energy.
Electromagnetic Spectrum The smaller the wavelength, the higher the frequency ,because all electromagnetic waves travel at speed C (Speed of light) and will therefore have more energy associated with them. For example, you can feel light energy in the form of thermal radiant energy.
Solar radiation This is a graph depicting what our eyes are sensitive enough to notice; the small part of the electromagnetic spectrum we call light. We experience this all the time. It is the visible, infrared, and ultraviolet parts of the electromagnetic spectrum
Where for Art Thou? • In 1928, Chlorofluorocarbons were not just a difficult and arduously long word, they were a wonderful find for refrigeration, where chemically inert, non-flamable, and nontoxic to humans. • But in1974, scientists began to ask where these chemicals were going. ?????
CFC and O3 • CFC is broken down in the stratosphere by a large amount of radiation and releases Cl in the atmosphere. • O3 (ozone) reacts with Cl (chlorine) in this manner: Cl + O3 -> ClO + O2 Which destroys the Ozone that protects the planet from UV rays. • ClO + ClO + sunlight -> Cl + Cl+ O2 Which releases more Cl to react with Ozone.
Holes In Our defenses:The Ozone is leaving us • 1977 Antarctica, team observed ozone concentrations dropping and plummeted 40% in 1984 covering an area larger than the USA. An Ozone Hole. • 1978 first regulation for CFCs: USA initiated a ban on spray propellants. • 1987 Ozone Treaty 47 nations agreed to phase out ozone-destroying chemicals by the year 2000. • Cancer is the main concern as more and more UV radiation gets through our weakened defense; the ozone layer.
Global Warming • Green house gases, such as water vapor and carbon dioxide, absorb infrared radiation to keep the surface warm enough for life. It’s sort of like a blanket to snuggle up in. • Since Industrialization, carbon dioxide concentrations have risen 34% • Such a rise in concentrations of greenhouse gases has warmed the planet, the oceans, and melted glaciers. • Global warming can cause wacky weather patterns and upset the balance of sensitive ecosystems such as coral reefs that can only survive in waters that stay a certain temperature all year round.
Carbon dioxide concentrations on the right, Global Temperature anomaly on the left. As CO2 concentrations have increased, so has the average temperature.
Quiz 1. If you Electrically charge a comb by brushing your hair, and then shake it, at a frequency of 1 Hz, what will this produce? • A sound wave • An electromagnetic field vibrating but no electromagnetic wave • An electromagnetic wave
2. When energy from the sun is absorbed by your skin it • Remains there as electromagnetic energy • Remains there as radiant energy • Transforms into nuclear energy • Transforms in to thermal energy
3. Refrigerators cool the objects inside. How do they affect your kitchen? • They cool it • They warm it • They don’t affect the temperature
4. A key step in ozone destruction by CFCs is • CFCs break down in the stratosphere to release chlorine • CFCs break down in the stratosphere to release carbon • Solar radiation breaks down O3 • CFCs directly combine with Ozone
5. A climate model that has been tested many times and found to be accurate is an example of • A scientific theory • A scientific hypothesis • A scientific fact
Answers • C • D • B • A • A Try some of the Review Questions at the end of the chapter for extra study.