Renewable Energy Resources
•Energy sources which naturally renew or replenish themselves over a period of time •Not depleted by use What do we mean by advantage and disadvantage? •Advantage means for a good effect, favorable gain, or desired end. •Disadvantage means for a bad effect, unfavorable, or undesired end. Biomass •Energy from any material that comes from plants or microorganisms that were recently living •Trees, branches, scraps of bark, and recycled paper are examples of biomass energy •The energy comes from burning it. •It becomes biofuel when mixed with gasoline, such as ethanol. Advantages 1.Can be stored and used when needed 2.Releases less harmful pollutants than gasoline 3.Uses materials that might normally be discarded Disadvantages 1.Growing crops for biofuels requires large amounts of land and pesticides. 2.Land could be used for growing food. 3.Pesticides can pollute. Wind •Wind energy is captured with wind turbines. •The blades turn a generator(located inside the tower), which creates electricity. •Groups of wind turbines are known as wind farms. •Found near farmland, in narrow mountain passes, and even in the ocean Advantages 1.Can be very efficient and cheap in places with steady winds 2.It’s clean, no pollutants Disadvantages 1.Wind is inconsistent. 2.Not a good source of energy in all locations. 3.Dangerous for bats and birds Hydroelectric •Energy made by flowing water •Hydroelectric power plants are located on large dams, which control the flow of a river. •A controlled amount of water flows through the tunnels and turns huge turbines which generate electricity. Advantages 1.Energy is inexpensive to harness. 2.Because rivers are everywhere, it’s an available resource. 3.Reliable because engineers control the flow of water Disadvantages 1.Damming a river causes a great environmental impact for people, plants, and wildlife. 2.Dependent on rainfall to fill reservoir 3.Expensive to build a dam Geothermal •Heat energy from deep within the Earth •Water is warmed by magma and pumped to the surface. •Geothermal heat pumps create heat for houses and other buildings. •Steam can also be brought to the surface and used to turn a turbine to generate electricity. • 90% of people in Iceland use this heat source. Advantages 1.Clean 2.Does not require another fuel source to produce it 3.Does not emit any harmful pollutants into the air Disadvantages 1.Not a wide spread source of energy 2.High installment costs to build power plants 3.Not easily transported Solar •Energy from the sun •Active solar energy uses technology to capture the sun’s rays (solar cells). •Passive solar energy gets energy from the way sunlight naturally changes throughout the day. (house might face a certain way to capture more of the sun’s rays) Advantages 1.Relatively simple technology 2.Little maintenance 3.Reliable and quiet 4.Free energy after purchasing solar panels Disadvantages 1.Energy cannot be created at night. 2.Cloud cover reduces power. 3.Works best if at the optimal angle towards the sun 4.Only converts 20% of the sun’s energy to electricity Generating electricity from renewable resources 1.Solar and biomass are used to induce heat. 2.The energy is used to heat water. 3.The water turns to steam. 4.The steam turns a turbine (geothermal). Or water turns it (hydroelectric) and wind turns it (wind). 5.The turbine shaft is connected to the shaft of a generator. 6.Magnets spin within wire coils to produce electricity.
https://phys.libretexts.org/TextBooks_and_TextMaps/University_Physics/Book%3A_University_Physics_(OpenStax)/Map%3A_University_Physics_II_-_Thermodynamics%2C_Electricity%2C_and_Magnetism_(OpenStax)/16%3A_Electromagnetic_Waves/16.5%3A_The_Electromagnetic_Spectrum
Waves •A disturbance that travels through space and matter •Transfers energy, not matter •Travel through electrical and magnetic fields Examples: light, microwaves, radio waves, and X-rays. Crest •The highest point on a wave is called the crest. Trough •The lowest point on a wave is called the trough. Wavelength •The distance between successive crests or troughs •Measures one complete wave Amplitude •The maximum extent of a wave measured from the position of equilibrium Frequency •The number of crests of a wave that move past a given point in a given unit of time •Measured in Hertz (Hz) Radio Waves •Longest wavelength •Lowest frequency •Coolest temperature •Examples: FM/AM radio stations, stars Microwaves •Need close proximity to transmitter •Examples: microwaves, routers, cell phones, stars Infrared Waves •“Infra” means below •These waves are just below visible light •Examples: remote controls, flames, lamps, stars Visible Light •All visible light •ROYGBIV •Examples: light bulbs, fire, stars Ultraviolet Light •Often called “black light” •Examples: sterilization, stars (sunburn anyone?), haunted houses X-Ray •High frequency waves •Examples: see inside organisms, airport security, dentist office, stars Gamma Rays •Highest frequency waves •Highest temperature (blue) •Examples: radiation therapy (cancer), sterilization, stars Studying the Universe •Astronomers use all kinds electromagnetic waves to study the characteristics (temperature, energy, color) of stars. •They can also use the EMS to determine chemical composition. Spectroscopy •A measurement technique which allows astronomers to see light that is absorbed, emitted, or scattered by materials •How do we know what stars are made out of? Star Composition •Use the class set of absorption spectrums to determine which elements are present in each star. https://www.pbs.org/video/nova-the-electromagnetic-spectrum/ Parallax •Astronomers can measure the distance of stars using a method called parallax. •They measure the star twice per year. •Every 6 months the Earth has moved nearly 186 million miles from it’s previous point due to its revolution around the Sun.
Science 8: Light Waves
www.youtube.com/watch?v=fm__GAlrBuQ Visible Light •The part of the electromagnetic spectrum, between infrared and ultraviolet, that is visible to the human eye. •Shorter waves – higher frequency and energy •Longer waves – lower frequency and energy Visible Light Spectrum •Produced when light passes through a prism, slowing the wavelength into each separate color. •ROY G. BIV - red, orange, yellow, green, blue, indigo, violet Colors •We see these waves as the colors of the rainbow. •Each color has a different wavelength and frequency. •Red has the longest wavelength and shortest frequency •Violet has the shortest wavelength and highest frequency. •Seen together, they make white light. Visible Objects •For an object to be visible it must produce its own light or reflect light. •Produces own light - Sun, candle, flashlight •Reflects light - Moon, mirror, glass Vocabulary •Opaque – A material that reflects or absorbs all of the light that strikes it. (wood, metal, cardboard) •Transparent – transmits light (glass, water, air) •Translucent – scatters light as the light passes through (wax paper, frosted glass) How light travels •Light travels in straight lines. •This straight line motion can be: •Reflected •Diffused •Refracted Absorbed Reflection •Occurs when parallel rays of light hit a smooth surface. •All the rays are reflected at the same angle. •Law of reflection: the angle of reflection equals the angle of incidence. •Angle of incidence - measure of the angle of a ray to the surface normal (90o to the surface) Diffusion •When parallel rays of light hit a bumpy surface. •Each ray obeys the law of reflection, but each ray hits the surface at a different angle. The light is scattered. Refraction •When light waves enter a new medium at an angle, their speeds changes. •The change in speed causes them to bend, or change direction. •Index of Refraction – a measure of how much a ray of light bends when it enters that material Lenses •When light traveling in straight parallel lines passes through an object that is curved like a lens, the light is refracted at different angles. •Convex or converging lenses bend light toward a central focal point. •Concave or divergent lenses bend light outward away from a focal point. Absorption •Light does not pass through or reflect from material, but remains in the material as energy. •What happens to the black surface? Color of objects •Color – Objects reflect colored light that is not absorbed. •We see objects color as the reflected color. Colors of Light •Primary •Red, Blue and Green •When combined in equal amounts, primary colors produce white light. •If combined in varying amounts, they can produce any other color. •Secondary •Yellow, Cyan and Magenta •Primary colors combined in varying amounts •Complementary - form when a primary color and a secondary color combine to make white. •Yellow and blue = white •Y + B = W or R + G + B = W Brightness •A relative expression of the intensity of the energy output of a visible light source •Brightness is determined by the light wave’s amplitude. •The greater the amplitude, the brighter the light. •Distance from light source also affects brightness. Nonrenewable Energy Resources
•Energy resources which do not naturally renew or replenish themselves •Depleted by use Fossil Fuels •Coal, oil, and natural gas •Formed when layers of buried plant, gases, and animals are exposed to intense heat and pressure over a long period of time •Currently the world’s primary energy source Coal •Fossilized carbon •Combustible (burns) •Recovered through mining •Occurs in layer or veins called coal beds or coal seams •Burned to produce heat or electricity Coal – 4 Types •Lignite – young, brownish, less value •Subbituminous –black lignite •Bituminous – soft, dense, black •Anthracite – hard, black lustrous, best Advantages 1.No shortage any time soon 2.Inexpensive 3.Reduces dependence on oil. 4.Creates jobs Disadvantages 1.Environmental impacts (burning, by-products, acid rain, increased greenhouse gases) 2.Mining impact on the land 3.Impact on miner’s health Oil •Known as petroleum or crude oil •Thick black liquid •Composed mostly of hydrogen and carbon (hydrocarbons) •Found in specific rock reservoirs •Extracted through drilling Advantages 1.Small amount produces a lot of energy 2.Easy to transport 3.Easy to produce 4.Constant reliable resource for years to come Disadvantages 1.Emits greenhouse gases 2.Spills cause water and land pollution and death to wildlife 3.Harmful emissions from plants can make people sick Natural Gas •Found deep in the earth and drilled to extract •Flammable, colorless, odorless •Made of methane and other hydrocarbons Advantages Compared to coal and oil 1.Less damage to the environment 2.Burns cleaner 3.More abundant 4.Safer 5.Cheaper 6.Best among fossil fuels Disadvantages 1.Gas leaks can be dangerous. Can cause explosions 2.Burning creates greenhouse gases. 3.Expensive infrastructure for production and distribution Fracking •A technique designed to recover gas and oil from shale rock •Drilling process similar to oil •A high-pressure water mixture is directed into the rock to break up the cracks and release the gas and oil inside. •Can be drilled horizontally or vertically Advantages 1.Can reach more oil and gas than traditional methods 2.Makes us less dependent on foreign oil 3.Less air pollution 4.Creates jobs Disadvantages 1.Keeps us from developing renewable resources 2.Uses a lot of water in the process 3.May pollute groundwater 4.Noise pollution 5.Chemicals used unknown Nuclear •The energy generated during nuclear fusion, especially when used to generate electricity •Fusion – two lighter nuclei fuse to form a heavier nucleus. Energy is given off. •Nuclear materials – uranium and plutonium. Advantages 1.Low pollution 2.Reliable 3.Low cost to produce electricity 4.Little fusion material needed to produce a lot of energy 5.Easily transported Disadvantages 1.Environmental impact in mining uranium 2.High cost in securing radioactive waste 3.Expensive to build a plant and purchase fuels 4.Accidents at plants are costly and dangerous Generating electricity from nonrenewable resources 1.Fossil fuels are burned to induce heat. Nuclear energy is produced from fusing atom nuclei. 2.The energy is used to heat water. 3.The water turns to steam. 4.The steam turns a turbine. 5.The turbine shaft is connected to the shaft of a generator. 6.Magnets spin within wire coils of the generator to produce electricity. Sound
•Vibrations that travel through the air or other media •When these vibrations reach the air near your ears you hear the sound. How Sound Travels •Sound waves carry energy through a medium (solid, liquid or gas) without the particles of the medium traveling along. •Sound travels as a longitudinal wave. How Sounds are Made •Longitudinal waves are generated when a source of energy forces the matter in a medium to vibrate. •This back-and-forth motion pushes air particles together, generating a compression, or moves the particles apart, generating a rarefaction. Medium •Sound waves must have a medium to travel through. •Gas – air is the most common •Liquid •Solid •In outer space there are no molecules to compress or rarefy, so sound does not travel through outer space. Speed of Sound •Depends on the physical properties of the medium it travels through. •Elasticity •Density •Temperature •At room temperature, sound travels through air at about 342m/s. Physical Properties of Media •Elasticity – the ability of a material to bounce back after being disturbed •Solid materials are usually more elastic than liquids or gases. •Particles of a solid do not move very far, so they bounce back and forth quickly as the vibration travels through the object, which allows waves to move faster. •Density – how much matter there is in a given amount of space •The speed of sound depends on how close together the particles of the substance are in the medium. •Temperature - degree or intensity of heat present in a substance or object •In a given media (solid, liquid, gas), sound travels more slowly at lower temperatures. Properties of Sound Waves •Intensity •Loudness •Frequency •Pitch •Intensity – the amount of energy the wave carries per second through a unit of area •Amplitude increases with increased energy •Measured in watts per square meter (W/m2) •Loudness – describes what you actually hear. •Though not the same as loudness, the greater the intensity of a sound wave, the louder it is. •Measured in decibels (dB) •Maximum safe level is 85 dB Frequency – the number of vibrations that occur per second Wavelength changes with frequency Measured in Hertz (Hz) 50Hz = 50 vibrations per second •Pitch – a description of how high or low the sound seems to a person •High frequency = high pitch •Low frequency = low pitch •Example: a young girl might have a squeaky (high pitched) voice, an older man might have a deep (low pitched) voice Doppler Effect •The apparent change in frequency as a wave source moves in relation to the listener •Sounds moving toward a person – Waves are at a higher frequency, so pitch appears to increase (high) •Sound moving away from a person – Waves are at a lower frequency, so pitch appears to decrease (low) |
Erik E. Mason
|