Experiment 2 Ohm's Law and Resistivity
In the first part of the experiment, you measured the potential difference (or voltage drop) across a resistor versus the current flowing through the resistor. Using Logger Pro, generate a graphical representation of your data, where the $x$ axis represents the current and the $y$ axis corresponds to the voltage drop. Drag the mouse through the graph window to highlight all data points. Click on Analyze in the menu bar and select Linear Fit from the scroll down menu. A straight line should be generated with a fit equation of the form y = m x + b. Save your graph to include in the lab report.
Do your data support the predictions of Ohm's Law, as stated in the Theory? Provide detailed discussion (about 300 words) in this regard. In the discussion, indicate the limitations of your experiment and possible sources of error.
In the second part of the experiment, you measured the voltage drop across ten increasingly long sections of Nichrome wire. Since the goal is to test Ohm's law ($R = \rho\, l/A$), you need to calculate the resistance and length values for each section. By selecting New Calculated Column from under Data in the menu bar, you should be able to calculate the resistance of each section using the Ohm's law equation ($R = \Delta V/I$). Also, by knowing the distance between two consecutive nails, you should be able to calculate the length of the Nichrome wire corresponding to each measurement. Save your measured and calculated data (as in Table 2.2) and include it in your lab report.
| Nail | Voltage $\Delta\,V\;(\text{V})$ |
Resistance $R\;(\Omega)$ |
Length $l\;(\text{m})$ |
| 2 | |||
| 3 | |||
| 4 | |||
| 5 | |||
| 6 | |||
| 7 | |||
| 8 | |||
| 9 | |||
| 10 | |||
| 11 | |||
| $I =$ | |||
Using Logger Pro, generate a graphical representation of your data, where the length of the active section of the Nichrome wire is plotted on the $x$ axis and resistance on the $y$ axis. Preform linear fit to your data and include the graph in your lab report.
Do your data support the theoretical prediction concerning the relation between resistance and length of a conducting wire? Provide detailed discussion (about 300 words) in this regard, indicating the limitations of your experiment and the possible sources of error.