FIGURE 13.

THREE VARIABLES IN A BASIC CIRCUIT.

Figure 14 (on the following page) shows the graph and a table of values.

This table shows R held constant at 10 Ohms as E is varied from 0 to 20

volts in 5 volt steps. Through the use of Ohm's law, you can calculate the

value of current for each value of voltage shown in the table.

When the

table is complete, the information it contains can be used to construct the

graph shown in figure 14. For example, when the voltage applied to the 10

Ohm resistor is 10 volts, the current is 1 ampere. These values of current

and voltage determine a point on the graph. When all five points have been

plotted, a smooth curve is drawn through the points.

Through the use of this curve, the value of current through the resistor can

be quickly determined for any value of voltage between 0 and 20 volts.

Since the curve is a straight line, it shows that equal changes of voltage

across the resistor produce equal changes in current through the resistor.

This fact illustrates an important characteristic of the basic law--the

current varies directly with the applied voltage when the resistance is held

constant.

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