J0701J0702J0703J0704J0705J0706J0707J0708J0709J0710J0711J0712J0713J0714J0715J0716J0718J0719J0720J0721J0722J0723J0724J0725J0726J0727J0728J0729J0730J0731J0732J0733J0734J0735CALIFORNIA STATE SCIENCE FAIR2006 PROJECT SUMMARYAp2/06Name(s) Project NumberProject TitleAbstractSummary StatementHelp ReceivedClaire R. ArakelianHow Temperature Affects Carbon ResistorsJ0701Objectives/GoalsDetermine how temperature affects carbon resistors' resistance. Preliminary research showed thatresistance is directly proportional to temperature, R=R(ref){1+a[T-T(ref)]}, where a is the temperaturecoefficient of resistance.Methods/MaterialsFor five 100 Ohm, 1/4 W resistors, measured each resistor's resistance [R(ref)] at room temperature[T(ref)] and resistance [R] at temperatures [T] of -198, -60, 23.6 (Room Temperature) 50, 100, 150, 200and 250 degrees C.ResultsMy average measured resistance at temperatures -198, -60, 23.6, 50, 100, 150, 200 and 250 degrees Cwere 103.88, 99.34, 98.26, 97.32 96.1, 95.3, 94.425, and 93.9 Ohms, respectively. I fit this data by use ofleast squares fit to R=-0.02T+98.74. From the slope, -0.02, determined the temperature coefficient ofresistance to be -0.0002 /C.Conclusions/DiscussionData didn't support hypothesis - resistance increased as temperature decreased. Further research showedthis as typical for carbon - a semiconductor. Semiconductors have an energy gap between the valence and conductive bands. Heating carbonintroduces more electrons in the conductive band decreasing resistance; cooling forces the electrons fromthe conductive band down to the valence band, increasing resistance. Semiconductor resistors have anegative temperature coefficient of resistance, metal resistors - positive.The effect of temperature on carbon resistors' resistance.Father provided materials; Aunt helped with charts and graphs; Professor Ares Rosakis, (Director ofDirector of Graduate Aeronautics Laboratories at Caltech), and Dr. Dale Conners, (Material ScienceDepartment at Caltech), for aiding me in interpreting the results and outcome of my experiment.CALIFORNIA STATE SCIENCE FAIR2006 PROJECT SUMMARYAp2/06Name(s) Project NumberProject TitleAbstractSummary StatementHelp ReceivedJoshua M. ArreolaThe Electrical FreezeJ0702Objectives/GoalsThe objective is to determine if exposing Duracell batteries to freezing temperatures for short periods oftime will cause them to die faster than Duracell batteries that are not exposed to freezing temperatures.Methods/MaterialsTo start, ten size-D Duracell batteries and twenty 15-centimeter long electrical wires were used. Withwire scissors, cut 1 to 1 ½ centimeters off the edges so the inside wires are exposed. Then with asoldering gun, solder two of the wires to the positive and negative sides of each battery. In the firstgroup, the five batteries that are going to be exposed to freezing temperatures (0 degrees Celsius), arelabeled as A, B, C, D, and E. In the second group, the other five batteries left at room temperature (20degrees Celsius) are labeled as A2, B2, C2, D2, and E2. Place the first group of batteries into the freezerat the same time. Take A out in 20 min., B out in 25 min., C out in 30 min., D out in 35 min., and E out in40 min. Leave the second group of batteries alone at room temperature. After removing the first group ofbatteries from the freezer, take all ten batteries and solder on ten 2.47 volt light bulbs to the other ends ofthe wires, with one wire being soldered on the bottom of the light bulb, and the other wire being solderedon the side of the light bulb. Observe the light bulbs every ten hours, and once the light bulbs start to dim,check more frequently. After all the light bulbs die, record how long each battery lasted in theobservation log. Transfer data to a graph.ResultsAccording to my graphs, the batteries that were exposed to freezing temperatures for short periods of timelasted longer than the batteries that were not exposed to freezing temperatures.Conclusions/DiscussionMy data shows that my hypothesis was incorrect. The batteries from the freezer actually lasted longer thanthe batteries left at room temperature. Even for short periods of time, it appears that batteries placed inthe freezer can help the batteries last longer.The purpose of this project was to determine whether freezing temperatures would have an affect on abattery#s life span.Mrs. Bloom, my teacher, for explaining things I did not understand. My Dad for showing me how to usea soldering gun. My Mom for helping me with ideas for my project.CALIFORNIA STATE SCIENCE FAIR2006 PROJECT SUMMARYAp2/06Name(s) Project NumberProject TitleAbstractSummary StatementHelp ReceivedRobert J. BecerraWhat Are the Effects of Weather on Laser Communications? Free-Space OpticsJ0703Objectives/GoalsThe purpose of the project was to test fog and rain effect on laser communications(free-space optics)systems using a laser transmitter of three different wavelengths and a receiver with a light detector. Thehypothesis was that the amount of light being scattered is a function of its wavelength and ultimatelyreduces signal strength in laser communications(free-space optics) systems.Methods/MaterialsThree different lasers(532nm, 650nm, 980nm) were set up in a transmitter circuit and aimed through aFog Testing Cube and Rain Simulator. A test signal was sent to the transmitter using a signal generatorand the output from the receiver was measured in decibels using a spectrum analyzer. I'd gather the resultsfrom the spectrum analyzer and log the data. I also set up a light scatter detection circuit at a 90 degreeangle to the laser to measure light scatter through fog and took measurements using a multimeter.ResultsMy results showed the 532nm green laser had the most scatter through rain and fog due to the fact thatshorter wavelengths scatter more than longer wavelengths. The 532nm laser communicated the bestthrough rain in the transmitter circuit. The 980nm infrared laser had the least scatter through rain and fogdue to its longer wavelength and had the largest fade margin. It's also the best to communicate throughfog. The 650nm red laser was the worst to use of the three and also had the smallest fade margin. Overall,the 532nm laser is the best to use in the transmitter circuit.Conclusions/DiscussionMy hypothesis was correct. The amount of light being scattered through fog and rain is a function of itswavelength. I was able to find out which wavelength had the most scatter