E9: Introduction to Linear Relationships Materials: Pennies, digital caliper, digital scale, cup to hold pennies on scale, your computer Initial definitions and givens: Scientists spend a lot of time making graphs. Plotting measured values on a graph makes it easy to see how one thing (e.g. the current in a circuit) depends on something else (e.g. the voltage supplied by a power supply). In this experiment we will plot some data by hand on graph paper and then learn to use the computer program Graphical Analysis to plot data and to determine the best straight line that can be drawn through the data points. In an experiment, you generally control something, such as the voltage output of a power supply. That value is called the independent variableand is plotted on the x-axis. Then you measure something, such as the current in the circuit. That value is called the dependent variable and is plotted on the y-axis.Always carefully label the x- and y-axes and include units (e.g. amps or volts) on your graph.
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