Physics B LAB: Graphical Analysis of Ohm’s Law Partners: Students will work in teams of three or less to complete this lab. Objective: Students will be able to determine the voltage of a cell from a graph of resistance versus current. Procedure: 1.
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Wire a circuit with a cell and one or more resistors. Draw a schematic diagram of the circuit and calculate the equivalent resistance. Record in the data table. Measure and record the corresponding current, connecting the ammeter in series. Do this 8 times without duplicating your resistance values. Up to 4 of these circuits may be a single resistor. The other 4 must be series, parallel, and combinations of series and parallel. Analysis: Rearrange the equation V = IR so that V is the slope of a “linear” equation (HINT: You’re going to have to divide, graphing the inverse of either current or resistance) Construct a graph from your data that corresponds to this rearranged equation. Calculate and clearly report the slope of the line. Conclusion: Is the line linear as Ohm’s Law predicts? How does this compare to the emf of 1.5 V for a D‐cell? What does this imply about the internal resistance of the cell? Rubric: Each student turns in their own paper, which includes a)
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ORHS Data table Rearrangement of equation Graph of data with line of best fit and triangle drawn to calculate slope Answers to questions in the conclusion section. Perkins, 2013