Electricity and Electricity Science Projects
Electricity science projects - can we make an electric circuit from everyday items, explain lightening, or even generate an electric current ourselves?
As we’ll see in a moment, the answer is yes, and whether we are designing electronic hobby projects, making a windmill generator or even simulating a lightening bolt with a static electricity generator … I think you’ll find that electricity science projects can be fun!
But before we grab our kite, key and a glass jar to perform (quite possibly our last) electricity experiment, we need to first explore the general concept. So how does it work? How does getting hot air from a hair dryer, or rubbing your socks on the carpet to shock your friend have anything at all in common with lightning? Can we come up with electricity science projects to demonstrate the basic concepts?
Bet we can …
Believe it or not, this is a tough question. In fact, we have to be careful how we use the term “electricity” or we get into quite a bit of trouble. For example, early electricity science projects were really about electric charge. Thales of Miletus (same guy on the magnetism page that said loadstone has a soul) noted that a piece of amber rubbed with a silk cloth would become "electrified". We know this is simply a buildup of electric charge on the surface of an object today, or an example of what we now call static electricity. With inventions like Van de Graff static electricity generators, we can even generate enough static electric "potential" that being on the receiving end of it’s shock might feel a bit like being struck by lightening. (Not a recommended science project for electricity!).
So what’s the big deal? We just define electricity as the build up of charge and we’re all set … right? Well, yes - and no.
“Electricity” is also used to describe the flow of electric charge. This is electric current and electricity science projects in this area would involve complete electric or even electronic circuits. By the way, once we have charges moving in a wire, our compass deflection or electromagnet experiments show we also generate a magnetic field. Folks like Hans Christian Oersted, Andre Marie Ampere, Michael Faraday, Joseph Henry and several others pioneered these findings. Hmmm … sounds like there must be some connection between electricity and magnetism, doesn’t it?.
"Electricity" is also a term used to describe doing something useful like running a set of electric hedge clippers, or lighting a dark room. This is a reference to electric power, and when you are told to turn the lights off so as not to waste "electricity", that is a reference to saving energy, be it correct or not. Electricity science projects in this area would involve lighting a light, making a motor run, making a coil of wire get hot like is done in a hair dryer or even making an electric generator. Oersted, Ampere, Faraday, Gramme, Siemens and Halske worked pretty hard on these items and are worthy of further study if you have the time to look them up.
So … is electricity the charge itself, moving charges (current), or using current to do something useful (power)? Well, at least loosely, the answer is yes to all three. In fact, electricity is used in other ways as well, but we’ll stop here. I think the point has been made that "electricity" is a term that has been used throughout history to describe several very different, but related concepts. It really isn’t specific enough to stand on it’s own.
But that’s ok. We’ll just break up our electricity science projects into several categories and move on. By the way, Wikipedia has a great article on the subject of Thales of Miletus, and the Columbia Encyclopedia at the link http://www.questia.com/reader/action/readchecked?docId=101242387 has a good overview on the history of electricity if you are interested in digging deeper with either of these subjects.
Lets take these one at a time:
Electric charge is an interesting subject, and if forced to make a choice, I would say this is the stuff "electricity" is made of … even at the risk of being scolded for using the term "electricity" as some kind of substance, even in electricity science projects. Here’s why …
Within a closed system (one that nothing gets into or out of), we cannot destroy the total charge contained in that system. We can only move it around. That’s called the law of conservation of charge. Think about that for a minute – it is significant.
Charge is also discrete. That means the total charge of an item is a multiple of some elemental value. That too is quite significant, and we even give it it’s own name. We call it the unit "e", or 1.60 x 10-19 Coulombs. Charles Augustin de Coulomb made massive contirbutions to the study of electricity and magnetism in the late 1700’s and the units of charge we use today still bear his name. It may appear that one unit of charge is quite small, but then again, it is the value of charge carried by either one electron or one proton. (They’re pretty small too). Two units of charge would be the value carried by two electons or protons. Three units of charge … , etc. That’s what we mean by discrete. 1, 2, 3 and nothing between (unless you want to dig into quarks, which is a bit beyond the scope of this discussion). I recommend looking up Robert Millikan if you want to see how this concept was proven.
Finally, regardless of what we are trying to show in our electricity science projects, charge only comes in two forms - positive and negative. The proton takes on the positive charge, and the electron the negative. Just as we see in the magnetism section for North and South Poles, with electric charges - opposites attract and like charges repel. And on the most fundamental level, that’s how charge works.
Since nothing in "electricity" really happens unless there is a difference in potential (or charge), that’s why I said if forced, this would be my choice on what "electricity" is made of … but that’s just me. I recommend "Goggling" monopole, dipole and even quadrupole if you want to learn more about how charges combine physically.
One of the things we did in the electromagnet experiment was to hook up the + and – terminals of a battery to create an electric current in a wire. But current is really just charge in motion, and by convention, we say that current "flows" from the positive terminal (high potential) to the negative (low potential), even though the electrons are responsible for transporting the charges around, or so the theory goes. In fact, we can complicate our lives and argue most of the day about whether it is really the electrons that move, or the holes they fit into … but for argument sake – let’s just agree that the electrons, (or negative charges), do all the moving in our electricity science projects.
Alessandro Volta is pretty much responsible for inventing the battery, and in his honor, we define electric potential, or the difference in value of static charge between two objects in terms of Volts. When we talk about current, we are talking about how many volts pass through a given point per second. And at the most basic level, that is how current works … the amount of charge passing a given point in a given amount of time.
It is also important to note that Christian Oersted figured out when current flows through a conductor, it also produces a magnetic field. Do you think he had a compass handy during one of his electricity science projects????
Ok, now it gets a bit harder to focus. Let’s step through this one a piece at a time …
In physics, the "Joule" is the unit we use to describe how much energy an object has. It may be because of it’s height above a reference point, like a ball sitting on a chair above the floor, or it might be because of it’s velocity, like a baseball heading toward a bat. It could also be because of a charge difference between a couple of metal plates that are close together, or even the state of "charge" left in our ipod’s battery to listen to music.
The "Joule" is derived from physics equations that relate how much work was done to get whatever we are looking at in the state it is in. For example, it took work to lift the ball off the floor and put it on the chair. If the chair was really a bench, and the ball was rolling, it took work to make it move as well. We would have to add the work to lift the ball, and to make it move to get the total energy the ball has.
… and "power” is how much work was done over a period of time.
If we are talking about a mechanical system, like lifting a ball onto a table, the power would be how much force we exerted to lift the ball, against the force of gravity acting to resist our efforts, over the entire time it took to get it there. The faster we lift the ball, the higher the power required to do so.
If we are talking about an electrical system for electricity science projects, we might be talking about how many "watts" it takes to run our hair dryer, and the manufacturer may use that as a representation of how hot it will get, or how fast it will dry our hair. In this example, the "power" is how much electric energy will get turned into heat as current flows through the wire inside the hair dryer. The wire itself resists current flow, and it is this resistance that causes the wire to get hot as the electrons (charge carriers) collide with the atoms that make up the wire. The higher the current for a given wire, the more electrons collide with surrounding atoms. This increases the movement of all atoms in the wire, which causes heat. As an example of how this might work, rub your hands together. The faster you rub them, the warmer they get. It isn’t quite the same thing, but it will give you an idea how motion can be changed into heat.
And that is how power works … it is how much work, or how much force is exerted over a distance in a given amount of time.
So, if we tell someone to turn off the electricity to conserve energy, are we really referring to the energy, or the power it would use if left on? Yup, even that is a bit fuzzy … but, I think we can say we really are referring to how much energy would have been used, since our electric bill is based on how many kilowatt-hours we used that month, which is a unit of power, but over a period of time - and that is energy.
Electricity Science Projects related to Charge
Actually the battery, as used in the "Turning on a Light Bulb" project can be used in electricity science projects involving charge, current and power. However, since nothing with electricity really happens unless we have a difference in potential, we'll put the battery here to start with.
Electricity science projects with a battery are certainly plentiful. Take for example a simple project of making a battery using stuff you have around the house. You can use a lemon, apple, potato, coins, even yourself, (as long as you're not planning on running anything that needs a lot of power).
How do they work? In each case there is a chemical reaction going on between the metals used inside the battery and something called an electrolyte, which is really just a fluid that easily transports charged particles called ions. Salt water is good example, so is lemon juice, vinegar, sulfuric acid, and many others.
Take a car battery for example. One of the plates is lead the other is lead dioxide. When the two plates are immersed in sulfuric acid, some of the lead from one plate and lead dioxide from the other are dissolved in a chemical reaction that creates lead, lead dioxide, hydrogen and sulfate ions in solution with some liberated electrons from the lead plate as a result. This is free charge ... or electric potential ready to go to work for you.
When the battery terminals are connected and you try to start the car, the free electrons rapidly move from the negative terminal to the positive terminal and combine there to create lead sulfate on that plate and water. At the same time, the positive ions are moving through the electrolyte and combining on the other terminal, also creating lead sulfate on that plate. Unchecked, the battery would soon die due to the acid becoming diluted with water and the plates being coated with enough lead sulfate that the reaction stops. The neat thing about this battery is that when we run the car our generator forces the current to flow back into the battery in the opposite direction and the reverses the chemical reactions. The lead sulfates that were deposited on the lead and lead oxide plates go back into solution and the water turns back into sulfuric acid. The battery is ready for you to start the car next time.
Four "make your own" battery projects are shown in hyperlinks above. There will be many more on the electricity science projects index soon. Check back often for updates.
Electricity science projects coming soon!
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