Title: Resistivity and Ohm’s LawSubtitle: Lab 22Lab Partners: Amber TelscherDate: December 29, 2015Abstract:This experiment helps us to take a closer look and to learn the meaning behind Resistivity and Ohm’s Law. This lab was designed to show the basics of electricity, such as, learning about electric current, which is defined as the number of charges passing through a cross sectional area of a wire over a period of time. One of the most basic forms of electricity found in nature, is lightning, which occurs when there is a buildup of electron charges within a cloud and is discharged via lightning. One important aspect of electricity is how it isconducted. This is done via metals such as copper, and allows free electrons to pass through,therefore, transporting electric charge from one place to another. Another aspect of this lab was to look at Ohm’s Law, which states that the current is proportional to the applied voltage, and varies depending on the resistance of the conductor that is carrying the current.Introduction and Background:This experiment helps us to take a closer look and to learn the meaning behind Resistivity and Ohm’s Law. This lab was designed to show the basics of electricity, such as, learning about electric current, which is defined as the number of charges passing through a cross sectional area of a wire over a period of time. One of the most basic forms of electricity found in nature, is lightning, which occurs when there is a buildup of electron charges within a cloud and is discharged via lightning. One important aspect of electricity is how it isconducted. This is done via metals such as copper, and allows free electrons to pass through,therefore, transporting electric charge from one place to another. Another aspect of this lab was to look at Ohm’s Law, which states that the current is proportional to the applied voltage, and varies depending on the resistance of the conductor that is carrying the current.The formula to show Ohm’s Law is R=V/I. An important concept to note here is that a highervoltage creates a higher current, which will yield a higher resistance, leading to a smaller current. In general, resistance of a wire is how hard the battery must push charges through awire. The resistance depends on the material that the wire is made of, the length of the wire,and the cross sectional area of the wire. With this being known, we will look at the interactions between those later in the experiment. Some examples of the things we will be testing includes; if you increase the length of the “wire”, what will happen, and if you reduce the area of said wire, what will be the affect. My hypothesis states that there is a proportional relationship between all of the variables in the equation, I=V/R. For example, ifyou increase the resistance, the current will decrease. This is due to the fact that circuits made with higher resistance material are harder to push charges through and will result in the circuit actually losing more electrical energy due to heat loss, limiting the electrical energy actually being distributed to electric devices.Method:This lab consisted of two experiments: the first experiment of this lab dealt with Ohm’s Law, and the second experiment dealt with the resistance of Play-Doh. For the first experiment, the materials used were; 4 AA batteries, two alligator clips, a digital multimeter, masking tape, a permanent marker, a ruler, and a 1 kΩ Resistor. This lab entailed of wrapping the fourAA batteries in masking tape and labeling them 1-4. Then the voltmeter was used to take a reading of the first battery, and subsequently each battery by adding one battery at a time and taking a reading between the addition of each battery onto a piece of masking tape that was used to keep all of the batteries in place while the experiment was being conducted. Thenext part of this experiment took the volt reading of the 1 kΩ resistor using the voltmeter. The second experiment required the following materials to be used; 3 alligator clips, aluminum foil, 2 AA batteries, a battery holder, a digital multimeter, Play-Doh, a ruler, scissors, Vernier Calipers. This experiment essentially had us test the voltage that was being passed through a cylinder shape of the Play-Doh and the effects of changing certain variables, such as, the length, the area, and the diameter of the cylinder of Play-Doh (wire). The set up to this experiment started by rolling the ball of Play-Doh into a 20 cm cylinder with an approximate diameter ranging from 10-15 mm wide. Once this was completed, the circuit could now be assembled by pushing two aluminum foil rods through the cylinder perpendicular to the long side of the Play-Doh. One of the alligator clamps was connected to the aluminum foil rod in the cylinder to the positive side of the battery holder. Once that connection was made, another alligator clip was used to connect the negative side of the battery holder to the metal probe of the black cord that was connected to the voltmeter. Lastly, the third alligator clip was used to connect to the metal part of the red cord that was attached to the multimeter, and was then used to complete the circuit by attaching the other end of the alligator clip to the other aluminum foil rod on the other side of the Play-Doh cylinder. This last side of the alligator clip was used to connect and disconnect the circuitbetween readings in order to take an average of the voltage being read for each of the situations the Play-Doh was rolled into. All of the volt readings were recorded in the tables provided for this experiment and was further used in later section to finish calculating values, such as resistance and current. One way that this particular experiment tested the voltage at different lengths, was by moving one of the aluminum rods closer to the other aluminum rod two centimeters at a time and reading and recording the voltages for each of the increments until there was only six total centimeters between each of the aluminum foil rods. For the second experiment, there was a part two, and this part entailed shaping the Play-Doh cylinder into different radius’s in order to see the difference in resistance by changing these variables, such as the length, and diameter of the Play-Doh wire within the circuit. The set up for part two was essentially the same as part one of experiment two, but just had us choose three different cross sectional areas to demonstrate how