Reference no: EM132579416
LEARNING GOAL 1: Use your knowledge of resistance, resistivity, and Ohm's law to measure the resistance of a wire and an unknown resistor.
LEARNING GOAL 2: Learn about the assumptions of particular models and how those assumptions affect the outcome of the experiment.
I. APPLICATION EXPERIMENT: MEASURING THE RESISTANCE OF A WIRE
The above link provides a simulation that presents resistance of wires of random cross-sections, lengths and conductive materials. Your task here is to plot and determine the relationship between length versus resistance and area versus resistance of a wire, and use your knowledge of resistivity to determine the resistance of a random wire of unknown resistance.
a) Open the link above and record the length, cross-sectional area, and resistance of several wires. Note that each time you click the area of a parameter such as length or cross-section or wire type, the value will be changed randomly. When you vary the parameters to get more data, you should be methodical and vary only one parameter at a time for a set of data. The goal in the next step will be to create plots of the data you take, so for example if a plot of length versus resistance would be made, you would want to keep area constant and click only the length section to get different lengths and resistances. You should do this about 10 or more times for length and about 10 or more times for cross-section.
b) Plot the data in Excel or a similar program so you have two graphs: Length (on the x-axis) vs Resistance (on the y-axis) and Area (on the x-axis) vs Resistance (on the y-axis). Connect the points of each the graph with a smooth line or curve.
c) What function shape does each graph appear to take? Recall that the resistance of a wire can be calculated using the formula R=ρ(L/A) where ρ is the resistivity of the material, L is the length of the wire, and A is the cross-sectional area of the wire. If one of the graphs is a curve, what happens if you plot the inverse of the x-axis values?
e) Using your knowledge of how resistivity works, given resistivities for various materials, and the measurements given for the random wire generated, calculate the cross-sectional area and the resistance of the random wire generated. Take a screenshot of the results page after you click "Submit" and include it in your lab report.
II. APPLICATION EXPERIMENT: THE RESISTANCE OF AN UNKNOWN RESISTOR
Apply your knowledge to measure the resistance of an unknown resistor. Recall Kirchoff's Loops Rules and Ohm's Law and answer the following questions about the battery and resistor circuit below:
a) If a voltmeter were to be placed at the Red and Black terminals next to the 800-Ohm resistor, what resistance R would be required for the voltmeter to read 1 Volt?
b) For the wire you dealt with in section d) and e) in experiment 1, what width would it have to have if it was 1 meter long and was placed in place of resistor R, in order to have the same resistance calculated in question a)?
1. How do you think an ohmmeter (or multimeter) works to measure resistance?
2. Explain briefly what the resistance of an object or material is a measure of.
3. How useful is it to be able to linearize data?
Attachment:- Electric Circuits and Resistance.rar