Current as a function of resistance
- Author:
- Allen Olson
But there's another set of possibilities! What if we treat Ohm's law from the perspective of having a set voltage (which is reasonable if you always use the same type of battery), then we may want to think about current as the output given a particular resistance as the input. The relationship is still given by Ohm's law, and it can be thought of as coming from the second version of the formula given at the beginning: .
But this time, we are treating R as the variable and V as the constant (or the coefficient).
What does the graph of current as a function of resistance look like?
Current as a function of resistance
Here we treat resistance as the input, so it is on the horizontal axis.
Current, as the output, is on the vertical.
Voltage is now the quantity that connects the two, and current is inversely proportional to resistance. As resistance increases, current decreases; but the relationship is not linear—at least not visually!
In the plot above, set the voltage to 40 (which we take to mean 40 V). What current would flow if the resistance was a) 10 , b) 20 , or c) 40 ?
In the plot above, set the voltage to -20 V. What current would flow if the resistance was a) 10 , b) 20 , or c) 40 ?