Unit Blog

In this unit our class focused on many different aspects of electricity. I had most trouble understanding how electrons are not supplied to make a current, but do cause a current to flow. I really improved on my teamwork skills when dealing with a disagreement, but in this unit I wish I could have worked on my teams podcast more and been a better help.
First we learned about charges, charge transfer, and polarization. The two charges are positive and negative, a positively charged particle is a  proton and a negatively charged particle is an electron. Opposite charges attract and similar charges repel, so protons and electrons attract. You can create a charge in an object three different ways; friction, contact, and induction. When using friction you rub objects together to give it a charge. If you take off a sweater the friction against the sweater and your hair causes the electrons from your hair to move to your sweater. This causes your hair to be positively charged and stand up from the protons repelling each other. Unlike friction, induction does not require any contact. For example, if you have a neutral object and you put a negatively charged rod near one side of the object it will attract the protons and repel the electrons. Once the electrons are on the other side you give them a pathway to the ground, taking away the electrons and leaving the object positively charged.
Polarization is when you separate the charges on an object so that they are on opposite sides. In the video on polarization we watched, we learned that just because something is polar doesn't mean it is charged. Also, objects can either be conductors or insulators. A conductor  allows charges to move through it while an insulator does not. An example of this is saran wrap on a metal bowl, since it is a conductor the saran wrap wont stick to it, but if it were made of glass it would stick. In order for the saran wrap to stick there has to be a force. According to Coulomb's law the force and the distance between the opposite particles are inversely proportional (F=Kq1q2/d^2).
Electric fields are what surround these particles. They are the area around a particle that influence (push or pull) another charge. So, like in Coulomb's law if the opposite charge is closer in the field the stronger the force between the particles. Since everything has particles and charges are flying all around us, you would think that electronics would be effected by this. On the contrary, they are provided wit electric shielding. Since computers have very specific and delicate circuit boards that could be destroyed by charges, the are protected by metal casings. since the outside of an electronic is metal, the charges are moved strait from the electronic to the ground instead of into the circuits.
The next important thing we learned about was electric potential energy and electric potential. Electric potential energy is the potential energy of charges, for example, by pushing like charges together you increase the electric potential energy. The electric potential is the voltage and can be found by the equation voltage=Electric potential energy / charge (V=PE/q). Capacitors in hospitals use electric potential energy to create a large voltage so as to revive patients whose hearts stop working. Another example is the flash on a camera. Here is a podcast to help explain: http://www.youtube.com/watch?v=k7FemQMMJjE&feature=youtu.be
The most important thing we learned about, and most difficult, was current. Current is the flow of particles through a wire to create electricity. Current is caused by the difference in voltage in a circuit. The current flows from high to low so if the voltage on one side of a battery is 20V but the other side is 0V and they are connected by a wire, then the current would run from the 20 V side to the 0V side. However resistance could change the amount of current flow in a circuit. In order to increase the resistance and decrease the current you would either make the wire thinner, longer, hotter, or change the metal to a less conductive one. In order to decrease the resistance and increase the current you would  have to make the wire thicker, colder, shorter, or make the wire a more conductive metal. There are two different types of current, Direct and Alternating. Direct current is when a current continues to move forward while alternating current moves back and forth. Electrons are relatively slow and many people believe that power sources add electrons to make current flow since electrons are what make current flow, but these sources of power supply two different voltages as to make the high voltage move to the low voltage and create a current.  This is an example of a direct current as well and is what is the popular type of current to use.
Next, we learned about Ohm's law and power. Power=Current x voltage (P=IV) and Ohm's Law states that Current=Voltage/Resistance (I-V/R). This means that the current and resistance in inversly proportional. Power measures the amount of watts used my an object. For example, a LED light could use a60 watts, but a CFL only uses 13 watts. The less watts used the less current used and more electricity and money saved!
Last but not least we talked about series and parallel circuits. Series circuits are like adding stoplights whenever there is a new appliance to the circuit, they all effect each other and the current decreases with every new appliance. Unlike series, when adding appliances to parallel circuits it is like adding lanes to a highway. This means that the current increases when more appliances are added they are not effected by each other making it popular in house holds and cars, however, it can be dangerous. This is why there are fuses in homes. If too many appliances are plugged into one home the current could get so great that the wires over heat and cause an electric fire. The fuse act as a current cutter and shuts off the current by melting and causing a hole in the circuit. This stop the flow off current, the over use of appliances and heat from the wires.