Nick's Blog site

Purpose

The purpose of this experiment was to demonstrate the law of conservation of energy; a law that states that energy is only transferred and transformed and never destroyed.

Procedure

In order to do this experiment, our trial team used a 3 beam balance to measure and record the mass of 4 different amounts of water. For each amount of water, we used a funnel and stopper to pour the water from a constant height of 73 cm. onto a waterwheel of plastic spoons. The force of the falling water would in turn make the wheel spin, and we would observe and record for each trial the number of rotations the wheel spun, and for how long it spun.

Calculations

For each trial, we are left with a water mass, a distance, a velocity, a number of rotations, and a time. For each trial, we first used this data to calculate the Potential energy in the system before the water was poured. Then, we would be left with a  value of energy in Joules. We used the formula PE= mgh for this calculation. For example, Trial 1 was calculated as follows:

PE= mgh = 0.3731kg x 9.8m/s^2 x 73cm = 266.92 Joules

The second calculation made for all four trials was Kinetic Energy. This calculation used the same set of measured data to derive the amount of energy exerted on the waterwheel in terms of mechanical energy, or energy of motion. The formula used for this step was KE= (1/2)mv^3 . In this formula, m is mass and v^3 is velocity cubed. So, the kinetic energy in Joules for trial 1 was found as follows:

KE= (1/2)mv^3= (1/2)(.3731kg)(14.6m/s^3)= 580.57 Joules

The third calculation was intended to derive the power of the spinning wheel for each trial, but the equation provided was unclear. (.5 x 1000kg/m^3 x 2.24m x velocity^3) I could not determine the proper order of operations in using this formula.

Results 

PE            KE

Trial 1          266.92J        580.57J

Trial 2         156.60J        665.28J

Trial 3        108.10J         235.12J

Trial 4          36.41J         1237.5J

Analysis

1. As you change the mass of the water, what changes do you see to the energy?

The mass of the water decreases with every additional trial. So, I can tell that as the mass of the water decreases, both the potential and kinetic energy in the system decrease, with the exception of KE in trial 4. I would consider this discrepancy due to human error. Aside from this, the water mass and the energy in the system seem to have a positive relationship.

2. Do you think energy can be a big amount with a little amount of water?

I do think that this is possible. I recall that both PE and KE are also dependent on either height (h) or velocity (v). If either of these values are increased enough, you can have a high amount of energy in the system with a relatively small amount of water.

3. Will there be more energy if there is more water, or more water?

As more water is poured onto the wheel, there is more potential energy that is converted into kinetic energy as it falls.

1. Greenhouse Gases Experiment

The objective of this experiment would be to demonstrate and observe the qualities of different greenhouse gases. We would use soda bottles to create 3 insulated environments, one with regular air, one with CO2 and one with Methane (CH4). The normal air bottle would act as a control system, and we would put thermometers in all three, and put them in the same exposure of sunlight. This would allow us to compare the different rates of temperature change.

2. Kinetic energy experiment

The objective of this experiment would be to prove that when an object is moved by gravity from a point of high potential energy to a state of high kinetic energy, the entire magnitude of potential energy can be converted to kinetic. To do this we would roll a ball of a certain mass down a ramp and have it strike a device that measures force. This way, we can calculate the energy it had in potential initially, and compare it with the force ( and then energy) exerted when it was all converted to kinetic.

3. Specific Heat Experiment

The objective of this experiment would be to determine the heat capacities. of three different materials. To do this, all three would be of the same mass, and would be heated to the same temperature in water. After the three masses are all the same heated temperature, they would be placed into 3 separate cups of water at the same temperature, but colder than the 3 masses. As the excess heat is transferred from each mass into the water, a thermometer can record each water temperature change after the systems reach an equilibrium. We can then use these measurements to calculate the specific heats for all three materials.

Introduction

Tom Vales had a very nice presentation to allow the class to see these energy alternatives in action. His novelty demonstrations of energy production were inspiring to keep research and development as a priority. The idea of producing energy from water temperature differentials for example was something I personally would have never thought could be done. Now with the demonstration, I have a wider perspective in potential resources for electricity, and I think it had the same type of effect with many students in the class. Some of his demonstations were especially noteworthy to recall.

Tesla’s coil

Vales’ homemade tesla coil worked just as effectively as one that could be seen in the Museum of Science. In conjunction with this fact, he explained that the copper bucket had nothing inside; it was simply a long, thing copper wire coiled around the bucket. When I saw the sparks it could produce I was amazed at what a relatively small scale model could produce. Furthermore, the demonstrations of the effects of the magnetic field were also interesting. I was able to see how expansive the range for available power was, and from reference of the demonstration I can tell that a model with an incredibly large production capacity would be needed to power the entire range of a room or home.

Silver Engine

The silver engine was also an interesting model to observe. It is suspended by a magnetic field, and its precision in design is stunning. It is also extremely fragile. Although it has little practical use for today’s power production, it was still a neat device to see in operation. If I recall correctly, the engine runs off hot air, so I imagine engines like these would work best in hot areas like the equator. It may not have much practical use now, but it may one day become essenial for renewable energy in the future.

Temperature difference engine

This engine was cool to see as well. Tom Vales said it produces electricity from the temperature difference that it comes into contact with. He also said the two temperatures of water in the cup were arranged with the colder water on top, and warmer water at the bottom. This caught my attention because normally water tends to arrange temperature in the opposite position. Warm water rises, while cold water sinks. I do not know why this switch happens, but I would guess that the engine is in some way responsible.

Steam Engine

The steam engine was fun to see on such a small scale, but what caught my attention was how primitive it seems in comparison to the other methods of electric production. Using an open flame for heat, generating a lot of noise and heat, it actually seemed a bit more dangerous than the others. Tom vales’ story of the accidents with steam engines substantiated that it is. On larger scale models, when there is not enough water in a steam engine, the instant conversion of not enough water to super-hot steam has caused violent explosions, and has killed many engine operators as a result.

 

Introduction

In my opinion, this plan shows that the President holds a clear and sober view on what needs to be done to stop climate change. He argues that we have a “moral obligation to future generations” to start solving this problem now. I absolutely agree with this perspective, and I think the President’s administration covers a lot of solutions that could help us solve the problem. Of these solutions, I do wonder how many will truly be feasible, and be able to implemented in the long run. I believe he includes policy to both wean America away from carbon emissions, and policy to support a future of minimal carbon emissions. He addresses both these aspects of the solution in his initiative of “Deploying Clean Energy” and “Building a 21st Century Transportation Sector’.” The report is right to say that climate change is upon us already, and administering a plan such as this properly would be a legitimate response to that fact.

Deploying Clean Energy

With regard to power plants, the presidents carbon emissions standard is a very long term goal. Since they apply to new power plants only, the standards will not have any downward on carbon emissions anytime soon. But, federal regulations could prove to be very useful to ensure the cooperation of future energy producers.

I am frankly a bit disappointed in the presidents plan to support renewable sources. He mentions government spending and support grow to many low efficiency solutions- wind, solar, geothermal and biofuels. This is absolutely better than nothing, but he does not mention implementation of nuclear energy, which is by far the highest yielding investment. Also in my opinion, the government shouldn’t merely spend money to build renewable energy independently, but should rather spend money to encourage and support a private market in renewable energy supply and demand. In this type of investment, the continued growth of renewable energy supply could be paid for by private investment and market competition rather than the governments pocketbook.

Clean Energy innovation is another action that has both short term and long term effects. The administration is investing in research and development of carbon capturing and sequestration of fossil fuels. This is a very good measure to implement so that we do not have to shift to 100% alternative energy too quickly. In coherence, to ensure that a steady pace of emissions reduction happens over the long term, they plan to have an Energy survey and report by the Federal government. This is a good type of enforcement for the country as a whole to keep pace with its goals.

Building a 21st Century Transportation Sector

Improving the transportation sector is also very important, because it accounts for almost one third of domestic greenhouse gas emissions. Within this sector, the category of heavy duty vehicles are the second largest emitters, even though smaller vehicles greatly outnumber them. This means they are energy intensive, and inefficient. The president’s goal is to lower the energy intensity of these

vehicles through federal standards for fuel efficiency. If enforced properly, this would be a practical measure for the short term reduction of carbon emissions. I think it is a good regulation, for cutting emissions where they hurt as few consumers as possible, but cut  a relatively large amount of emissions at the same time. The report projects an estimated 270 million metric tons of carbon kept out of the air by these standards, but personally, I question the probability of this actually happening. This assumes the standards are enforced effectively, and I think this would be hard to do. Passenger vehicle fuel economy standards raise the same question. How difficult will it be to hold a federal minimum of 54.5 miles per gallon for all vehicles? Only time can truly tell if it is feasible.

The plan also considers action for the long term to actually introduce alternative energy in the transportation sector. The plan stresses the potential in biofuels and fuel cells for alternative energy production. I agree that there is potential in both, but I believe the most practical investment is in fuel cells, due to the low efficiency yield of biofuels. The goal is to bring alternative energies down to a cost competitive rate with gasoline and diesel, and I think the action to further develop car batteries, as well as keep consumers informed of the potential savings in electric cars are both good steps to achieve this goal. The plan cites a current electricity cost equivalent to a gas price of $1.41 per gallon, which, if it is accurate, provides a very good long term incentive for consumers to switch to hybrid or completely electric cars as gas prices steadily rise.

Conclusion

I think this plan is for the most part practical and achievable, but I am skeptical about the actual reliability of these promises being followed through with. I believe at some parts the policy could be altered so that the government’s investment has a higher return and is more effective in cutting greenhouse gas emissions, such as nuclear energy production, and nurturing a new market in renewable energy sources. Although improvements can be made, I think the policy includes very responsible regulations for the short term and long term challenge of moving away from fossil fuels. I hope they are enforced, and I hope the goals set in investment and innovation are met and even pushed further in the future.

 

Introduction

Our last class, we visited the Museum of Science to learn about alternative energy beyond the classroom.  We visited four exhibits, all linked to energy production and consumption. We learned the technical and statistical aspects of wind and solar production, and got a better idea of their contribution in the grid. We also compared these renewables with all sources of energy. Finally we looked at efficient energy consumption, and what it looks like on a household level. These four exhibits each helped to expand our perspective on energy production and consumption in a different manner.

Catching the Wind

This exhibit was about the efficient harnessing of the wind to generate electric power. Using a visual representation, the exhibit illustrates the mechanics of transforming wind motion into energy. The diagram disassembles the standard wind turbine so the inner workings can be observed, and each parts function is explained. Some interesting parts that I was not aware of are things like the yaw

motors, which turn the blades of the turbine towards the directions of the wind in order to maximize efficiency.  This exhibit also shows the different designs of wind turbines, and classifies them with respect to their output efficiency. The most efficient design of course is the commonly observed straight bladed turbine called “Proven 6”. Other designs however include the skystream, the AVX1000, and windspire, which all vary greatly in their design.

Energized!

Energized is an exhibit focused on the problem of limited resources of fossil fuels. These resources will eventually run out, so this exhibit aims to educate people on the pros and cons of alternative energy sources. The exhibit also goes in depth in the renewables such as solar energy, and the science of energy storage. We looked at an interactive part of the exhibit that let us shine light at different angles on a solar panel. The exhibit recorded

the output, and it showed us that a direct angle is the most efficient angle for solar panels. Another interesting part of the exhibit was the magnetic flywheel. This device is one attempting to solve a very big problem with renewable energy production, and that is energy storage. The energy storage device is produced by Beacon Power Corporation in Massachusetts. This device can compensate for fluctuations in energy demand by receiving excess electricity to convert it into mechanical energy. This is why the vessel has a large spinning wheel component. When demand is high, the spinning wheel can act as a generator and provide the additional output.

Conserve At Home

This part of the museum was about how to reduce energy demand per household by making reasonably easy measures in your lifestyle. The most interesting and interactive part of this exhibit was the light-bulb comparison. The exhibit allowed visitors to try to power three different lightbulbs using a hand crank generator.  The first light, LED, is an 8 watt, and it can light up its surroundings with a few easy cranks of the wheel. The incandescent on the other hand is listed as a 40 watt, and this lightbulb barely glows no matter how fast you try to crank the generator. This stark difference gives everyone a common perspective on how much energy certain lightbulbs can conserve, making this a very good part of the exhibit. The exhibit included other informative sections on domestic conservation, such as how to reduce the amount of trash we produce by simply recycling. The exhibit stated that without recycling, we produce and average of 4.4 lbs of trash per person per day. After recycling, we produce 2.9 lbs of trash per person per day. This is a very solid difference to show people the value of separating their recyclables.

Investigate!

This exhibit allows for the visitors to act as scientists themselves. There are several experiments that are set up to demonstrate laws of motion. I used the motion tracker. The motion tracker shows your position versus time on a graph. As you walk along the pad, sensors track your position, and records it. On the graph, the actual slope of the line tells the visitor his speed of motion at different times. The other experiment we observed was one concerning the acceleration due to gravity, or g. It is known that on all objects, g is constant regardless of mass. The only thing that impedes g is air resistance. So, our experiment dropped a ball with a larger mass and a ball with a smaller mass from the same height, at the exact same time.  We expected them to hit the bottom at the exact same time, but in fact the larger ball hit an instant before the lighter ball. This proved that in our atmosphere, air resistance is a factor and can not be negligible in an object’s acceleration due to gravity.

Conclusion

I think these exhibits are a good review and a good addition to what we have covered in class. There is a large kid demographic for the museum, so having interactive exhibits are a great idea for teaching the next generation about the importance of alternative energy, and energy efficiency. As for students and adults, the exhibits still provide very informative data. I am glad the museum brings attention to the issues of energy research and efficiency.

Introduction 

Throughout the world’s use of nuclear power, here have been several very significant accidents regarding radiation leakage. These disasters associate fear with the entire nuclear industry, and combined with the history of nuclear weapons destruction, can easily ruin the demand for nuclear energy  expansion. The two relatively largest nuclear disasters to ever occur were in Chernobyl, Ukraine in 1986, and Fukushima, Japan in 2011. Both disasters called for immediate evacuation of the surrounding area due to extreme levels of radioactivity. By learning about what caused these accidents, we can be sure that mistakes are never repeated, and nuclear power does not harm any more people.

Chernobyl

The disaster at Chernobyl was undoubtedly the result of gross negligence in safety design and operation. The plant consisted of four light water reactors, with no external radiation containment structure. This design flaw is critical, because radiation can be contained well with the proper design. The accident was caused by a poorly designed control rod in the reactor. Operators had disabled the shut down function of the reactor the day before the accident, so when the power surge in the fuel rod occurred,  resulting steam pressure caused the entire core to overload, and explode. This was followed by a second explosion, which scattered half of the reactor along with its graphite control rods, and highly radioactive fission fragments.

Two people were killed by these explosions, and 28 people were killed due to radiation exposure during emergency response actions. Those killed had been

exposed to levels up to 20,000 millisieverts (mSv). The natural dose of radiation for a person is about 2,5 mSv per year. These extreme dosages were caused by the fission fragments that were around the close proximity of the explosion site. However, lighter radioactive particles were released into the atmosphere and carried by wind. The closest town to Chernobyl, Pripyat, had to be immediately evacuated, and residents still received doses of 50 to 100 mSv. Ultimately, the accident created a 4,300 square kilometer zone unfit for residence, due to levels of radiation that would exceed the normal 2,5 mSv per year.

Fukushima

The Fukushima disaster introduces a whole new threat to nuclear energy: natural disasters. Exactly 5 years ago, on March 11th, 2011, a tsunami caused by an earthquake in Japan damaged the cooling process and power supply of the

Fukushima nuclear plant. The result was an overheating that caused 3 nuclear reactors to meltdown. Throughout several days there were a number of failures causing this meltdown, and a hydrogen explosion. This leaked radioactive fission fragments into the surrounding water, as well as dispersed lighter fragments into the air.

What is more unnerving about Fukushima is that it was not caused by design or operator negligence. The plant was designed to withstand earthquakes and even significant tsunamis, but the Fukushima tsunami still put the nuclear plants 5 meters below sea level, causing in the meltdowns and explosion. Not only did the tsunami disable the reactors, but it also disabled people’s ability to respond effectively. Radiation monitoring could no longer be used, so the plumes of radioactive clouds could not be tracked to notify locals to evacuate. This is why in the course of days the prime minister’s evacuation order from the proximity expanded from an initial 2km to 20 km.  Nobody was killed due to radiation exposure, but some workers have been exposed to as much as 250 mSv during the disaster, and have to be closely monitored. Still today the area of Fukushima is under reconstruction, and many people are still living in government subsidized housing. Hopefully, an unnerving situation such as this never causes us to lose control of our nuclear reactors, because if natural disasters remain a threat to nuclear reactors, nuclear reactor will be considered a threat to health and safety.

Works Cited

“Chernobyl Accident 1986.” Chernobyl. World Nuclear Association, n.d. Web. 11 Mar. 2016.

“What Happened?” Fukushima on the Globe. N.p., n.d. Web. 11 Mar.2016

Introduction

I think this movie is an excellent production to enlighten today’s citizens on the realities of nuclear power. It is designed to dispel the shadow left by the generation of anti-nuclear activism, and put the benefits of nuclear power into perspective. They make the argument even stronger by having previous anti-nuclear environmentalists preach this message, and admit to their faults in opposing nuclear power. Their argument is strong because they systematically address the concerns of anti-nuclear advocates, and then clearly explain why their concerns are either no longer legitimate, or are extremely outweighed by the benefits of nuclear power. These concerns could be categorized into three topics: Operation safety, radiation, and environmental damage.

Operations Safety

The movie first described Chernobyl and Three Mile Island, and what exactly went wrong. They admitted to the magnitude of these accidents, but then explained why they would not occur again. Chernobyl was an unsafe, and uncontained reactor, and its meltdown was caused by negligence. Three mile island was caused by operators not following proper procedure. These were both significant accidents, but they argue that our lesson is learned, and technology has now made for much safer operations. Nuclear reactors like the one in Chernobyl are not used, and there is always sufficient containment. In addition, they also prove that we now have fail safe reactors, which automatically shut down if they get too hot, so meltdowns can not be repeated.

Radiation

The movie also addresses people’s deep fear of radiation exposure by having nuclear reactors in operation. They enlighten people on the subject by explaining that just about all things on earth emit small amounts of radiation, and that humans are not harmed by small quantities. They visit various places where people live and measure radiation there, and they show that radiation around a nuclear plant, or contained nuclear waste is the same amount of radiation in a normal US city. Indeed, they even show places where natural radiation is much higher than the normal measure, simply because of their elevation, and closer proximity to cosmic radiation. This shows that normal operations of nuclear plants have absolutely no negative externalities.

Environmental Damage

They also recall how in the 60’s and 70’s, being an environmentalist was synonymous to being anti-nuclear. Activists feared radiation emissions (which has already been adressed) and the problem of nuclear waste. They address the nuclear waste problem by showing that proper storage is completely safe, and that technology is allowing for the use of a breeder reactor instead of a light water reactor. Breeder reactors can recycle and reuse plutonium fuel many times over, significantly reducing the amount of waste produced.

Their second argument is that environmentalists have been unrealistic about the growth of solar ad wind power. It is simply too expensive, and is intermittent power, which would require fossil fuel backups. Greenhouse cas emissions cannot continue, and they bring up the reality that singles out nuclear as the only power that can complete with fossil fuels. Alongside this fact,  it also releases even less CO2 than the production of solar panels. As a success story, they look to france who went nuclear in the 70’s, and now enjoy vast amounts of cheap energy with half the emissions per capita than that of Germany, who strives to go solar. With all these benefits to nuclear, the movie brings to our attention that we already have a solution to clean energy, and all we need to do is unite as a planet and invest in it.

 

 

Introduction

Thermoelectric devices are incredibly useful for modern energy production and heat control. The two most widely used thermoelectric devices are those that transfer heat into a system to produce electricity, and adversely those that use electricity to transfer heat out of a system. Both functions have very practical applications, and I find the science behind their heat control very interesting. I will explore both functions of thermoelectric devices by first discussing thermoelectric materials. Then we will see how its properties allow both the generation of electricity, and the transfer of heat from a system.

Thermoelectric Generation

Thermoelectric materials are usually semiconductors that facilitate the Seebeck Effect. In the Seebeck effect, we essentially have the same process as what happens in the silicon layer of a solar panel. But with these systems we have instead two semiconducors: one heated and one cooled. With an electrical circuit between both heated material and cooled material, electrons tend to transfer into the cool material. So in this system, we create a positive field of holes (the heated side) and a negative field of electrons (cooler field) . This electron transfer is what allows for a magnetic field, and voltage to be produced in the system.

This diagram describes the process well. You can see that heat is the input in one material, and  in effect the negative charge produced by the semicoductors flows through the other material, producing a voltage.

Thermoelectric Heat Pump

The Peltier effect is the inverse of this property. This effect states that, “whenever a circuit of two dissimilar materials passes current, heat is absorbed at one end of the junction and released at the other.” (Power Practical) So, in this system, electricity is an input to create a heat transfer, or heat pump.

This diagram of the Peltier effect describes the inverse. In this system, a voltage is the input in the same set of semiconductors, and is used to create a cooler field and a hotter field.

Applications

If a thermoelectric cooler functions with the heat absorbtion side in an insulated space, the heat within that space will be absorbed into the device, and trasferred to the space outside the system. This is how most fridges or freezers can keep food in constant cool temperatures. Beyond food storage, the ability to remove heat from a space is essential for any heat sensitive materials, such as medicines or biological samples.

Thermoelectric generators are also very useful for energy conservation. Any significant heat exhaustion is otherwise wasted energy being emitted from a system. So, adding thermoelectric generators to any exothermic system (heat emitters) could improve efficiency with greater electrical output. Even batteries can be replaced by small scale thermoelectric generators that can draw energy from heat in its surroudings. As research continues on these devices, even more uses will arise in the future for these generators.

Sources

“How Do Thermoelectrics Work.” Power Practical. Power Practical, n.d. Web. 03 Mar. 2016.

Alphabet Energy. “How Thermoelectric Generators Work.” Alphabet Energy. N.p., 2009. Web. 3 Mar. 2016.

Rouse, Margaret. “What Is Seebeck Effect? – Definition from WhatIs.com.”SearchNetworking. TechTarget, n.d. Web. 03 Mar. 2016.

Introduction

Iceland has a very unique advantage over other countries in terms of domestic energy supply. The country happens to be located on a geographical sweet spot. Traditionally, we assume this means they are living above a sea of oil or coal, but this is not the case. Iceland is fortunate because they  live on a global hot spot. The heat radiates from the land, littering the country with hot springs and volcanic activity. This is fortunate because the natural heat can be captured to produce geothermal energy, which is  a both clean, and renewable power source. So, where does this natural heat come from, and why does Iceland get all of it?

Why Iceland?

The earth’s crust can be considered as tectonic plates, which constantly interact with the liquid magma mantle that lies below it. The process of subduction and convection keeps the tectonic plates moving above the mantle like an incredibly slow conveyor belt–subduction pushes one plate below another and into the mantle, while convection pulls plates apart, allowing for hot magma to rise and cool to form new land. The atlantic ocean as we know it was created due to this process, and just like the ocean that surrounds it, Iceland is also the product of convection. The mid atlantic ridge splits the country in two, and the convection activity makes the heat from the earth’s mantle very accessible from the surface.

Utilization

Iceland does not take this natural resource for granted, and has done an amazing job utilizing it. Since heat is so accessible, almost half of the heat harnessed is pumped directly from the land into the space heaters of local homes. A total of 40% of the heat harnessed is transformed into electric power. The other majority of the heat is transformed into electricity. This initiative is a success story similar to the thriving solar industry in Germany. With the nurturing finances of the Icelandic government, a whole new market in geothermal utilities was allowed to stabilize, and has all but replaced the demand for fossil fuel energy. Today, between heat and electric output, the heated ground satisfies half the island’s total energy demand. Incredibly, the other 49 percent is drawn from different renewable sources such as hydroelectric dams. This is an amazing accomplishment for a country so riddled with natural sources of clean energy. Yet Icelander’s still look to the future with greater goals, and profits in mind.

Innovation

With the combined effort of geothermal companies and the Icelandic government, research is being conducted in the use of supercritical steam power

for the geothermal plants. The Iceland Deep Drilling Project aims to use the hotter spots deeper in the convection ridge to harness supercritical steam. This method, previously used in nuclear energy, is projected to increase the efficiency of the turbines by a factor between 5 and 10 times its current output.

With an endless source of energy, Iceland is now looking to profit from its geothermal energy bank, by exporting electricity. It has found demand in Britain, who is in need of a constant flow of power to supplement their intermittent wind turbine output. The result is the prospect of a 600 mile long, 1 gigawatt capacity cable running in the sea between the two nations. If accomplished this would be an amazing deal of  for both countries energy interests, as well as an even more efficient utilization of Iceland’s natural geothermal resources.

Sources

“Geothermal.” Orkustofnun. National Energy Authority, n.d. Web. 29 Feb. 2016.

Mims, Christopher. “One Hot Island: Iceland’s Renewable Geothermal Power.” Scientific American. Scientific American, 20 Oct. 2008. Web. 29 Feb. 2016.

E.L. “Power under the Sea.” The Economist. The Economist Newspaper, 20 Jan. 2014. Web. 29 Feb. 2016.

Runyon, Jennifer. “Geothermal Energy in Iceland: Too Much of a Good Thing?” Geothermal Energy in Iceland. Renewable Energy World, 4 Mar. 2013. Web. 29 Feb. 2016.

Objective

The objective of this experiment was to analyze how light intensity and light color act as variables in a solar cell’s efficiency of generating a voltage. We are looking to derive a distinct relationship between each variable and the voltage produced.

Procedure

To perform this experiment we needed a flashlight, a small solar panel, colored filters, a ruler, and a computer programmed data recorder. Our first step was to ensure that our solar panel was properly connected to the data recorder. Once we knew data was being recorded properly, we gathered data for the single variable of light intensity. To do this, we used the ruler to measure 5 different distances above the solar panel: 0cm, 4cm, 8cm, 12cm, and 16cm. At each of these distances, we turned the flashlight on pointing directly at the solar panel, and let the computer record the voltage produced in a 30 second span. The computer gave us 10 numbers for each trial, and we found the average for each set of 10 in Excel. After averaging all 5 sets of data, we were left with 5 measures of voltage: One to correspond with each intensity level. The data is shown below.

Distance (cm):      0            4              8              12        16

Voltage (V):     0.4690    0.4394     0.3972    0.4061   0.3882  

After gathering this data, we then singled out the variable of light color. To do this, we kept the intensity of light at a controlled distance of 0cm for all trials. However, every time we turned on the flashlight and recorded the voltage output, we had a different color light filter in between the flashlight and solar panel. The first trial let only purple light through to the solar cell. The second let only yellow light, the third only pink light, and the fourth only red light. We averaged out each of the four data sets that were recorded just like the first stage of the experiment. Our results were us 4 measures of voltage: one to correspond with each color of light.

Color:            Purple     Yellow      Pink        Red

Voltage (V):   0.3689     0.4639      0.4382     0.4215

Conclusion

In order to draw conclusions for the data sets of each variable, we used Microsoft Excel to graph our data. We will first analyze the graph representing the relationship between light intensity and voltage.

As we can see by our graph above, none of our voltage measurements are too far from the linear trend line. This indicates that there is a relatively strong correlation between the distance of the flashlight from the solar panel, and the voltage that the solar panel produces. We also can see that the slope of the trend line is negative. This tells us that as the distance between the flashlight and the solar panel increases, the voltage that is produced decreases. What we also have to take into account though, is that we are analyzing the relation of light intensity and voltage output. We know that as distance increases, light intensity decreases. So in this case, despite the negative slope of the graph, we can conclude that there is a positive relationship between light intensity and voltage output– meaning that as light intensity increases, so does the voltage output.

To draw conclusions for the variable of light color, we will consider the  bar graph form our results below.

If we look closely, we can see that each color yields a different voltage output. What I notice, is that the more light transparent colors, such as yellow and pink, yield a higher voltage than less transparent colors, like red and purple. I would explain this by reasoning that the more light a solar panel is allowed to absorb by a colors transparency, the more voltage the solar panel can produce. This would indicate a positive relationship between transparency and voltage output.

Another significant thing that this graph shows is the stark difference of voltage produced by cooler hues like purple, and warmer hues like red. While their transparencies are closely related, they lie on opposite ends of the light frequency spectrum, as shown below.

According to this figure, the wavelength of purple light waves are much shorter than red light (roughly 300 nanometers shorter.) When comparing their difference in voltage output, we can conclude that solar cells absorb longer light wavelengths more efficiently than shorter wavelengths. This would explain why purple light yields less voltage than rel light.