In class, Tom Vales introduced us to some amazing devices. Some of these devices were invented in the 18th century. The purpose behind some of them was mainly to generate electricity. It is really interesting for me to see how the development of making generators has become from the past up until the present. It is very crucial for every electrical engineering student to have knowledge about these various electrical inventions.

The most interesting device in my opinion was the Mendocino Motor.

There is a magnet on the base of the motor (under the armature) that provides a vertical magnetic field for the part of the coil that is closest to the base. This magnetic field, combined with the current flowing through the coil closest to the magnet, generates the rotational force.

This motor, like many DC motors, has a requirement that the current flowing through the coil reverse itself every 1/2 rotation. This solar motor works by having the solar panels automatically reverse the current in the coil as it rotates.

It does this by having TWO solar panels for each coil. The panels are on opposite sides of the armature so that when one is on top, the other is on the bottom.

When one panel is illuminated (the panel on top) the current flows clockwise. When the other panel is illuminated (because it rotated to the top), this second panel drive current through the coil in the opposite direction as the first panel.

The easiest way to understand this is to look at the simple schematics picture. It shows two solar cells (panels) connected to the coil.

One implication of this design is that if both panels are illuminated equally (light coming from above and below), the motor will not spin at all. Can you see why? All of the current flows in a circle around through the cells, with no current flowing through the coil.

Another invention was the Tesla Coil. 

A Tesla coil is an electrical resonant transformer circuit invented by Nikola Tesla around 1891. It is used to produce high-voltage, low-current, high frequency alternating-current electricity. His invention of the alternating current motor set the stage for the power and lighting systems now used every day around the world.

References

http://en.wikipedia.org/wiki/Tesla_coil

http://www.chessplayingrobot.com/id4.html

President Obama has announced, “So today…I’m directing the Environmental Protection Agency to put an end to the limitless dumping of carbon pollution from our power plants and complete new pollution standards for both new and existing power plants.” This is the first proposal in the President’s new climate initiative. The President also called for expanded efforts to use clean energy” and for the US to lead the world in bold actions to “combat climate change.”

Investing in Clean Energy is one of the initiatives. It is an obvious way to reduce greenhouse gas emissions. By changing the way we use sources to produce energy, we will cut down the rate of greenhouse emissions by a big factor. It’s understandable that shifting to a clean energy costs the government a big amount of money, but this money goes to ensure long-term sustainability.The Administration focused on four areas, including energy sector reforms that are preconditions for sustainable clean energy development, energy efficiency, low carbon energy, and clean transport.

Promoting Sustainable Landscapes; to help countries that put forward ambitious programs to reduce greenhouse gas emissions from deforestation and forest degradation (REDD+), the United States announced it would dedicate $1 billion over 2010-2012 as part of the U.S. contribution towards the “fast start financing” reflected in the Copenhagen Accord.

One of the important initiatives is increasing fuel economy standards. Greenhouse gas emissions are not only produced when generation energy but also when using this generated energy in different ways. For example, in the transportation sector, heavy-duty vehicles are the second largest source of greenhouse gas emissions. The Obama Administration set the first-ever fuel economy standards for Model Year 2014-2018 for heavy-duty trucks, buses, and vans. These standards will save 530 million barrels of oil. By setting new standards and reducing fuel consumption, transportation sector will produce much smaller greenhouse gases. The efforts will continue to improve the efficiency of moving goods around the country.

I personally think, for more reduction of emissions, the developed countries need to join efforts to be environmentally friendly. As we all know that a single hand can’t clap.

References

http://www.whitehouse.gov/sites/default/files/image/president27sclimateactionplan.pdf

http://www.whitehouse.gov/sites/default/files/Climate_Fact_Sheet.pdf

President Obama’s Climate Initiative—The Bad News and Good News

When the tour was announced, I felt a great deal of excitement although it seemed a bit scary at first. This tour had been on the list since I opened up to the world academically , fortunately, I hadn’t been able to explore the NRL as an individual for security restrictions. So, it was a great chance for me to go with the class. The exploration was divided mainly to a lecture and a field walk. After the security check, we were asked to wear radiation detectors that looked like pens with two optical openings on both ends and a scale measurement inside of it.

One of the important information is that the NRL is meant for commercial use and energy production. It’s used only for scientific experiments. Although in the past the NRL used to treat cancer via a procedure called Boron Neutron Capture Theory and was one of the best at it, the NRL has stopped this procedure due to a lack of doctors. However, it’s enough for the NRL to be the hope to improve nuclear reactors of the future. As far as sustainability is concerned, greenhouse emission reduction is a regarded by the researchers.

It was essential for me to know hoe the reactor works. As the lecturer explained, there are two methods of nuclear reactions one of which is nuclear fission of uranium atoms, which is the one used here. An nuclear fission is illustrated by the picture below.

In the nucleus of each atom of Uranium-235 fuel are 92 protons and 143 neutrons, a total of 235 particles so fantastically small that their size is difficult to imagine. Around this nucleus whirl 92 electrons, which are even smaller particles. If the nucleus were as big as a baseball, an electron on its outer rim would be a mere speck nearly a mile away.

The arrangement of particles within uranium is unstable and the nucleus disintegrates easily. When the nucleus absorbs an extra neutron, it breaks into two parts or splits. This process is known as fission (see diagram below). Each time a nucleus splits, it releases two or three neutrons. Hence, the possibility exists for creating a chain reaction.

The rate of fissions in the uranium nuclei is controlled chiefly by six control blades of boron-stainless steel which are inserted vertically alongside the fuel elements. Boron has the property of absorbing neutrons without reemitting any. When the control blades are fully inserted, they absorb so many neutrons from the uranium that there are not enough to cause a chain reaction. To put the reactor into operation, the control blades are raised very slowly. As they absorb fewer and fewer neutrons, more and more neutrons are available to cause the splitting of uranium nuclei, until finally enough neutrons are being released to sustain a chain reaction.

In addition to the fuel and control blades, one other factor is essential to the operation of the reactor. This is a moderator-coolant, which is ordinary or “light” water in the case of the MITR-II. Since uranium nuclei do not readily absorb neutrons moving at the high speeds with which they leave fissioning nuclei, it is necessary to slow them down with a “moderator”. For this purpose about one-half the volume of the reactor core consists of water.

One of the fascinating things was the control room. It is a room that filled up with monitors and switches and in this room you can keep track of everything happening in the reactor. The word SCRAM was used all around the reactor. This word stands for Safety Control Rod Axe Man, which is an old method used to shut down the reactor.

References

http://web.mit.edu/nrl/www/reactor/fission_process.htm

In my team meeting, we went though what we want to present to the high school students. First consideration was to choose an experiment to perform in front of the students. We finally settled on falling objects experiment. This experiment combines Newton’s second law (F= m*a) with wind resistance (drag) in order to relate our project to sustainability. We will be using NXT with two sensors placed in the starting placed and the end place which is the ground. The results we are trying to get are the velocity, acceleration, and time of the falling objects. We divided the work to three parts as to save time. Each part was given to two or one of our team members. Wind resistance is the main point behind the experiment because it is relevant to both the experiment and sustainability.

Solar cells are in fact large area semiconductor diodes. Due to photovoltaic effect energy of light (energy of photons) converts into electrical current. The term “photovoltaic” comes from the Greek φῶς (phōs) meaning “light”, and from “Volt”, the unit of electro-motive force, the volt, which in turn comes from the last name of the Italian physicist Alessandro Volta, inventor of the battery (electrochemical cell). The term “photo-voltaic” has been in use in English since 1849.

Solar cells produce electricity in three steps;

1. Photons in light hit the solar cells and are absorbed by semiconducting materials, such as silicon.
2. Electrons (negatively charged) are knocked loose from their atoms, causing an electric potential difference. Current starts flowing through the material to cancel the potential and this electricity is captured. Due to the special composition of solar cells, the electrons are only allowed to move in a single direction.
3. An array of solar cells converts solar energy into a usable amount of direct current (DC) electricity.

In this lab, we discovered the relationship between a light source and solar cell. In two different experiments, we measured the voltage output of the solar cell. In the first experiment, using a flashlight and solar cell connected to the NXT in order to measure the voltage output, we placed the light source in different distances and measured the voltage output of the solar cell. It was noticeable that the further the light source the lesser the voltage output. In the second experiment, the distance of the light source was kept constant and we changed the light color using colored filters. Therefore, the voltage output varies because of changing the color of the light leads to changing in the energy of the photons according to the following formula:

Where E is the energy of the photon, h is Planck constant (6,626·10-34Js), λ is the wavelength, and c is the speed of light.

Experiment (1)

The main point of this experiment is to determine the relationship between the solar cell and the light source in terms of the distance. Basically, if the light source is placed far from the solar cell, the light intensity becomes smaller resulting in smaller voltage output. The graph below illustrates the relationship.

Therefore, we can conclude that the voltage output is inversely proportional to the distance of the light source.

Experiment (2):

For this experiment, we had to figure out the relationship between the wavelength of light and its energy of the photons. As stated before by the equation, the energy of the photon (E) is inversely proportional to the wavelength. Therefore, light consisting of high energy photons (such as “blue” light) has a short wavelength. Light consisting of low energy photons (such as “red” light) has a long wavelength. Below is a chart demonstrating the voltage output of different colored filters.

The data from the chart proves the voltage output from a red light is smaller than the one from a blue light.

References

http://www.pvresources.com/introduction/solarcells.aspx

http://en.wikipedia.org/wiki/Solar_cell

http://www.pveducation.org/pvcdrom/properties-of-sunlight/energy-of-photon

The class went on a trip to MOS museum to study wind,  solar energy and investigate the exhibit. What captivated me at the beginning of exploring the museum was the electricity section since I’m an electrical engineering student. Fortunately, the timing was perfect for me to attend the breathtaking presentation of the electricity exhibit. As I walked into the section there was a guide explaining the exhibit to the audience. The guide introduced Nikola Tesla’s invention.  His invention of the alternating current motor set the stage for the power and lighting systems now used every day around the world. We also were introduced to Faraday’s cage shown in the picture below.

We were shocked when the guide was absolutely confident as walking into the cage that nothing would happen to him. Surprisingly, not even a single lighting went into the cage. As he explained, it is because the cage’s wall is conductive so that when the electricity hit it, it will be absorbed by the cage’s wall and prevented from going inside. So, the guide proved that staying in the car while a lightning storm is actually safe. Another experiment that dazzled my eyes, there were two adjacent conductive poles with ring shaped tops. When the guide applied high electricity to the poles, the high electricity could overcome the insulating air so we could see it flowing from pole to pole like lightning. As the guide changed the value of current, certain musical tones were produced. This happens when current is being released pushing the air around it, so our eardrums receive these what we can call waves of pushed air making us hear different tones according to the amount of the released current.

Wind exhibit

The first aspect I explored in this section was the different types of wind turbines and their efficiency. Below is a picture of turbine types that were shown.

And below is a table of the differences;

It is clear that the longer the turbine and the bigger the blades the more electricity we can generate as explained mathematically below.

P= power in watts  ρ = The air density (1.2kg/m³ @ sea level and 20° C

A = The swept area of the turbine blades (m² square meters) 

V = wind speed ( meters per second)

Power of gears also plays an important role in generating electricity. There was an interlocking gears model for us to see how they fit together to form part of the gearbox inside the nacelle of a wind turbine as shown below.

It is predictable that the right wheel doesn’t require a great force to make it spin unlike the left wheel. If an equal external forces are applied to both wheels and then removed, the left wheels will keep moving for a much longer time than the right wheel. In other words, the deceleration of the left wheels is smaller than the one of the right wheel. That is because the external force that has been applied to the left wheels will be generated even more from the first wheel to the other.

Environmental impacts of wind turbines

While wind turbines have a much smaller impact that fossil fuels, they can affect the environment in different ways such as land use and birds deaths.

Land use

Although each turbine takes up very little space, wind farms require roads and electric substations. Careful selection of locations can minimize the impact. Smaller, building-mounted turbines are also an alternative. Offshore turbines use no land, but must avoid known shipping channels.

Bird deaths

Birds and bats can die in collision with turbines. Power lines, glass-covered skyscrapers, and cats can kill just as many. About 40,000 birds are killed by wind turbines every year, compared with 2,000,000 birds killed from oil spills. Careful consideration in placing wind turbines can minimize this number.

http://www.ask.com/question/what-is-nikola-tesla-famous-for

http://www.windgenkits.com/faq.htm

http://www.mos.org/

Introduction to Faraday’s law and electromagnetism

Before we start learning this law and electromagnetism, we have to become familiar with the general relationships that exist between electricity and magnetism as follows:

1. Electric current flow will always produce some form of magnetism.
2. Magnetism is by far the most commonly used means for producing or using electricity.
3. The peculiar behavior of electricity under certain conditions is caused by magnetic influences.

Faraday’s Law states that changing magnetic fluxes through coiled wires generate electricity (currents and voltage). In other words, the induced electricity is proportional to the change in magnetic flux, so the greater the change is the more electricity generated. A cupper coil and moving magnet are commonly used to explain the law as shown below.

As the magnet moves back and forth, electricity is being generated because of the following reasons.

1. A change in magnetic flux. Magnetic flux is a measurement of the strength of the magnetic field, which is calculated by multiplying the average of magnetic field B by the area A it goes through. Given by this equation Φ= B.A and the unit used is the Maxwell.
2. Whenever we have a change in magnetic flux, we’ll generate an electromotive force (emf) that will create a current going through the coil. This induced current is going through the coil in a direction to minimize the change in the magnetic flux. The way to look at it mathematically is by the following equation.

emf= – the change in Φ/ the change in time. where the negative sign by Lenz law indicates that emf will oppose the change in Φ.

Experiment and procedure

In the lab, we used a generator that works just like the picture above. And by connecting it to a voltage probe to the NXT, we could calculate the voltage output of the generator using Excel sheet. Simply, our experiment was to correlate the number of shakes of the generator, in a thirty second time interval, with the voltages (or more precisely the sum of the square of the voltages) that the generator generates. Now, we did five runs with different number of shakes. We proved that the more shakes the greater the voltage output. In other words, for the induced voltage to be increased, the change in magnetic flux (Φ) has to be increased too. For our experiment, time seemed to play no role, because for each run we had the same time interval (30 s). Below is a graph showing the relationship between the voltage output and the number of shakes.

It is obvious that the more shakes we do the more electricity generated.

Conclusion

This Faraday’s law is very important and helped with a number of applications. For instance, musical instruments. Musical instruments like electric guitar, electric violin etc have a pick-up device attached to them. It consists of a fine enameled copper wire wound on a magnet. When the metal strings of the guitar are strung, the vibrating string cuts the magnetic flux of magnet linking the coil due to which electric current is induced in the pick-up’s coil. It is modulated by the mechanical vibrations of the strings. This electrical signal is then amplified and recorded by suitable devices. In addition the phenomena of electromagnetic induction is also used in instruments and machines like Induction motors, Induction Sealing, Audio video tapes, Hall effect meters, Faraday Disk etc.

http://www.youtube.com/watch?v=qWu82nJS42I

https://www.google.com/search?q=faraday’s+law&source=lnms&tbm=isch&sa=X&ei=BrltUquEJ-354APy7YGQAQ&sqi=2&ved=0CAcQ_AUoAQ&biw=1518&bih=748#facrc=_&imgdii=_&imgrc=0jy-zUMFNM0aOM%3A%3BIZml3mJYTnupZM%3Bhttp%253A%252F%252Fsites.suffolk.edu%252Fekprime%252Ffiles%252F2011%252F04%252Ffaradyanim.gif%3Bhttp%253A%252F%252Fsites.suffolk.edu%252Fekprime%252F2011%252F04%252F05%252Ffaradays-law-with-flashlights%252F%3B321%3B293

http://202.141.40.218/wiki/index.php/Applications_of_Faraday%27s_law

Basic Electricity prepared by the Bureau of Naval Personnel.