# Wrapping It Up

So there are many ways to look at a simple formula like Ohm's law. Even though there are only three quantities involved, there are six different graphs that can be plotted:
• Current as a function of voltage
• Current as a function of resistance
• Voltage as a function of current
• Voltage as a function of resistance
• Resistance as a function of voltage
• Resistance as a function of current

## Which of these are linear?

Check all that apply
• Current as a function of voltage
• Current as a function of resistance
• Voltage as a function of current
• Voltage as a function of resistance
• Resistance as a function of voltage
• Resistance as a function of current
For Ohm's law, the main feature of the formula is proportionality. Even when the graph is non-linear, it is a proportional relationship... we just call it "inversely proportional." When the input is multiplied by a certain factor, the output is divided by that same factor... when the resistance is doubled, the current is cut in half (assuming the voltage remains constant).