Electrical Resistance

Part 1: Answer the following questions (20 points)
1. Name and describe the components needed to make a complete circuit. A complete circuit requires a battery, wires and a light bulb. 2. Compare and contrast a series and parallel circuit. Give at least one way that they are alike and one way that they are different. Both series and parallel circuits must have all the components of a complete circuit in order to work. These two circuits differ in the way the electrons are able to flow. In a series circuit the electrons flow in one direction and along one path only while in a parallel circuit the electrons may flow through different paths along any complete available circuit. In a parallel circuit more electrons will flow through the circuit as compared to the series circuit. 3. Ohm’s law is represented by the equation I = V/R. Explain how the current would change if the amount of resistance decreased and the voltage stayed the same. Ohm’s law states current is dependent on voltage and resistance.

As in any mathematical equation if we change one variable in the equation on one side and leave the other variable constant, the other side of the equation will change as well. In this case since current is equal to voltage divided by resistance. If we keep voltage the same and decrease the denominator (resistance) our resulting number will increase. Thus the current will increase. If we look at this from a physics stand point we can see that if we decrease the amount of resistance the electrons are faced with, then the electrons will feel the voltage more and thus they will flow at a faster rate. 4. Define resistance and describe what would happen to a light bulb if the voltage increased but the resistance stayed the same. Resistance is what slows the flow of electrons in a circuit. As described in the previous question, Ohm’s law states current=voltage/resistance. If we keep resistance the same and increase the force at which the electrons are being pushed at (voltage), then the electrons will flow faster, thus the current will increase. Part 2: Design your own circuit (40 points)

Design a circuit and draw a circuit diagram using the proper symbols. Your circuit must contain a battery, a light bulb (if you would like to substitute another item that uses electrical power you may), a switch, an ammeter, and a resistor. After you draw your circuit, complete the questions which ask you to describe the circuit that you have created. You may hand draw the circuit and scan or fax the worksheet to submit for grading. Or you may use a draw/paint program to create your circuit in the space provided.

Question 1: Is the circuit you created a parallel, series or a series/parallel circuit? Support your answer with a description of this type of circuit. The circuit I made is a series circuit since there is only one path for the electrons to flow. Question 2: What is the purpose of the resistor in your circuit? The purpose of a resistor is to decrease the current in the circuit. This will slow down the flow of electron movements. Question 3: How does the switch work?

When the switch is pulled up to on it will connect the circuit as it completes the circuit and the electrons will now flow and the light will turn on. When the switched is turned off the circuit becomes incomplete and the electrons can no longer flow and the light will turn off.

Question 4: Describe the path of the electric current through your circuit. When the switch is turned on to complete the circuit, the electrons will flow from the negative end of the battery towards the positive side. When the electrons reach the light bulb electrical energy will be converted to radiant energy. Question 5: Explain how your battery works. (You may want to look at lesson 3.02) What are some possible materials you could use to make your battery? The battery works by having two metals of different electron attraction. The electrons will then flow from the metal that has the higher tendency to lose electrons to the metal that has tendency to gain electrons. I could use Lithium and copper and the electrons will flow from the lithium to the copper.