For the past two weeks, our science class has been reviewing, learning, and investigating the topic of electricity. There have been eight main topics that all students were required to learn, of which included: how charges interact with one another, how charges can be transferred, electric currents, conductors and insulators, how resistance affects currents, Ohm’s law, series vs. parallel circuits, and the difference between voltage, current, and power. The class was divided into groups of three, and each group created a presentation on one of these specific topics.
One of the first things our class did was that we each had to build an electrical circuit with only a battery, a magnet, and a wire. Mine is shown on the video at the side. The point of this project was to make us understand how an electrical circuit works. An electric circuit is a “complete, unbroken path through which electric charges can flow.” The charges in an electric circuit flow from the negative side to the positive side because the electrons are negative. Negative charges repel other negative charges, just as positive charges (protons) repel other positive charges. However, positive and negative charges attract, which is why the electrons flow towards the positive side. In my experiment, the electric current (the continuous flow of electric charges through a material) flowed through the copper wires, through the copper spinner, and back through the other wire. With the force of the magnet pushing the spinner up, and the electricity causing it to move, the spinner executed its task and started turning.
The law of conservation of charge states that charges are neither creates nor destroyed, they are only passed along. Charges can be transferred through three different types of methods: friction, conduction, and induction. When objects are transferred through friction, their electrons move when the two items are rubbed together. In the process of conduction, items can be charged through direct contact, in which electrons transfer from the item with more negative charge to the item with more positive charge. In the last method, induction, objects do not have to touch to transfer charges. It is caused by the electric fields of the objects, which either attracts or repels electrons.
The next topic is based on conductors and insulators. Conductors help ease the flow of electricity, and its atoms contains electrons that are loosely bound together. Good examples of conductors are silver and copper, like I used in my project. An insulator slows down the flow of electricity, and its atoms are tightly bound together. Good examples of insulators are plastic and rubber. Rubber is usually found wrapped around wires. This is so that when people touch the wires, they don't get shocked.
The fifth topic that we learned was about resistance. Resistance is how difficult it is for charges to flow from materials. There are four things that affect resistance: heat, material, width and length. Take, for example, two cables. One is wide and the other one is half the width, the wider cable will allow more energy to flow than the latter. In some cases, resistance is a good thing. With hairdryers, showers, etc., resistance is needed to produce the friction that causes the heat.
Ohm's Law states a simple equation, Resistance = Voltage/Current. In Ohm's Law, the greater the resistance is, the less the current is and vice-versa. Voltage is a difference in potential energy between two places in a circuit. Voltage causes electric currents because the pressure from the voltage will push the current. Sometimes, the voltage may not be enough to push the current, or it might be too much. That is why you cannot put a 220 volt appliance in a 110 volt socket, or a 110 volt appliance in a 220 volt socket.
There are two types of circuits, the series circuit and the parallel circuit. In series circuit, the current can only take one path through all of the resistors. This means that if something goes wrong and one of the resistors burn out, the resistors that follow it will also burn out. In contrast, parallel circuits have multiple paths that a current can take, so if a resistor burns out, the other continues working. An example is with christmas lights, sometimes one of the twinkly, colorful lights stops working, and all the others behind it stop shining as well. However, if you take the lighting of a house, for example, if one of the lightbulbs run out, the others stay on.
The last topic is the difference between voltage, power, and current. This also has an equation: Power = Voltage x Current. This means that if either voltage or current increases, so does the power.
This is basically what we've been talking about since school started, and it will be the base of what we learn for the rest of the school year. Personally, I don't understand this topic very well, and I am having difficulties. However, I plan to get better, and eventually succeed in understanding all of the topic.
