1 ENVIR 202 EARTH AIR WATER 7 i 2003 EXPERIMENTS FOR UNIT 1 ENERGY GETTING STARTED P B RHINES F STAHR E LINDAHL Because our textbook relates to energy use technology history and impacts only we need some text on the science background We come from many backgrounds so some of you will be familiar with some of the science core others will not The idea is to move from where you are now in scientific training a step or two higher The lectures and notes and lab projects are all aimed at this Read the sections most relevant to your experiments with the most attention and then begin to spend some time reading the others We will hand out more notes discussing the background ideas behind the experiments Everyone should look at the basics of energy conservation that is using conservation in its scientific sense energy is neither created nor destroyed energy evaluation how do we measure it energy conversion from one form to another the quantitative idea that work transfers energy from one object to another and work again by its scientific definition is equal to force times distance the force exerted on a body times the distance the body moves The experiments below give many different views of these basics Everyone should carry out two of these during the Energy Unit and become familiar with most of the others by watching and talking to the teams doing them Part of the exploration phase of the experiments involves writing notes in your lab book on some of the other experiments and where relevant relating them to the experiments you have done There are likely more experiments than we need and so a few of these may become demonstrations You will spend about 3 lab periods on each experiment you do 2 different experiments in each of the units of the course for a total of 6 during the term We begin with a Getting Started guide Once you have successfully carried out these fairly explicit experiments use the rest of the time available to make explorations more on your own you could look more deeply into what you have done for example changing the rate of heating or input power to an experiment to see how everything else changes or testing for errors energy losses in the experiment and then improving the apparatus or making more quantitative measurements working with an application of the experiment or going deeper into the physics behind it or considering the scale of the experiment compared with the scale of the phenomenon in the natural environment Both the getting started phase and the later exploration phase are important to carry out 2 We will later on hand out notes with more detailed discussion of all the experiments A SHORT LIST OF EXPERIMENTS FOR UNIT 1 Energy E1 Suns and Rainbows sunlight s colors its power and energy and what happens when it passes through the atmosphere E2 Lenses and Mirrors concentrating energy and taking apart sunlight ray by ray E3 A Model River generating a flow in a water channel with electric propulsion energy conversion electrical to mechanical the reverse of hydropower E4 A Heat Engine an engine using heated air to make mechanical energy E5 My Candle Burns at Both Ends measuring the useful energy content of fuels energy conversion hydrocarbon heat E6 Blowing on Your Soup conduction and convection thermal energy flow in solids and fluids E7 A Solar Pond energy conversion and storage solar to thermal E8 Your Next Car The hydrogen fuel cell energy conversion chemical to electrical and reverse E9 Bicycle Power generating electricity from mechanical energy which comes from chemical energy E10 The World s Simplest Electric Motor a solar powered motor based on simplicity E1 SUNS AND RAINBOWS examining the solar spectrum This lab experiment explores the sun s radiation which is the primary energy source for most things on Earth Sunlight is one kind of electromagnetic radiation distinguished mostly by being visible Other kinds of invisible radiation are radio waves x rays and infra red heat While they seem so different they are distinguished by their wavelength more on waves wavelength and frequency is in the extended notes coming later but for now just think of a wave on water with peaks and troughs the wavelength is the distance between two peaks Visible light falls in the range of wavelength between 400 and 700 nanometers or 0 4 to 0 7 micrometers microns or 0 4 to 0 7 x 10 6 meters Our eyes and ocular nerves sense the wavelength and that is what we call color across the colors of the rainbow from red orangeyellow green blue violet the wavelengths go from longer to shorter 3 red light has about 650 nanometer wavelength and blue light about 450 nanometer wavelength Here we want to look at both the wavelengths colors that make up light and also its intensity the rate of energy flow the power in a light beam then think about the greatly different temperatures of the moon and Earth have such different temperatures we have an atmosphere and the moon does not A GETTING STARTED 1 Examine the hand held spectrometer which breaks light into its component colors DO NOT point it directly at the SUN First look at the fluorescent lights and flashlights in the lab not lasers and record what you see 2 Look at outdoor light NOT THE SUN DIRECTLY and record what you see including the visible wavelengths of light which range from 3 There is a relationship between the color of light radiated from a hot object and its temperature Look at a candle flame and perhaps a Bunsen burner flame The highest temperatures are in the lower part of the flame with lower temperatures above at some height the burning flame ends where amount of burnable gas is not enough to support combustion Record what colors you see where The result from studies in physics is that the radiated power varies like the 4th power of the temperature T4 in degrees Kelvin or just Kelvins that s temperature in degrees Celcius plus 273 Zero Kelvin is absolute zero the point at which molecules cease to move and no radiation occurs the dark sky at night represents about a 3 degree above absolute zero 3K temperature of the Universe Light with wavelength greater than red is called infrared We can t see it but we can feel it it is heat waves carrying heat Take a silvery dish or piece of aluminum foil which reflects waves very well it s a mirror and place it close to your face See if you can feel the reflected heat waves that are constantly being radiated from your face Measure your skin temperature at the same time Although we can t