Section 25.11 Power in Circuits
Energy is transferred from chemical potential energy stored within the battery to the charges that move around the circuit. As the charges travel around the circuit, they lose energy through resistors. Since there are a lot of charges moving in a circuit, it is often useful to talk about the power delivered to resistance elements:
Subsubsection Key Ideas
Definition 25.11.2. Power.
The Power delivered to a resistor is the current flowing through the resistor multiplied by the voltage:
\begin{equation*}
P = IV\text{.}
\end{equation*}
Subsubsection Activities
Activity 25.11.1. Sensemaking.
Use some of your sensemaking techniques on the power equation. What are the units? Why might this equation be useful?
Activity 25.11.2. Power to Energy.
How can you use the power to determine the total amount of energy delivered to the resistor?
Activity 25.11.3. Light Bulbs.
Old incandescent light bulbs are usually rated to provide \(60 \mathrm{~W}\) of power. When you plug it into the wall at \(120 \mathrm{~V}\) the light bulb will light up. What do you think is the resistance of the light bulb when it is plugged in (in Ohms)?
