Definition 25.9.1. Ohm’s Law.
Ohm’s Law relates the voltage across a resistor to the current flowing through that resistor by a quantity known as resistance:
\begin{equation*}
V = IR
\end{equation*}
Section 25.9 Ohm’s Law
Assumption 25.9.2. Linear Resistors.
A linear resistor or Ohmic resistor is one that has a resistance \(R\) that is constant (it is the same no matter what current is flowing through it).
Devices or circuit elements that obey a linear relationship between the current and the voltage is considered to be "Ohmic". Ohm’s Law is particularly useful to determine relationships between the voltage, current, and resistance of a resistor element. Be very careful when using Ohm’s Law for other elements if you do not know if they are Ohmic. A common misconception is that Ohm’s Law can be used for lightbulbs. In general, lightbulbs are considered to be non-Ohmic, and therefore may not obey the linear relationship that is Ohm’s Law.
Exercises Activities
1. Sensemaking: Units.
What are the units of resistance in terms of other units you have used?
