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Learning Introductory Physics with Activities

Section 10.13 RC Charging Circuits

Exercises Activities

1.

What is the derivative of the function \(f(t) = Ae^{-\omega t}\) with respect to \(t\text{?}\)
The circuit below contains a battery, a bulb, a switch, and a capacitor. The capacitor is initially uncharged and the voltage of the battery is \(V\text{.}\)
A circuit diagram with a battery, open switch, light bulb, and capacitor.
Figure 10.13.1. A circuit diagram with both a light bulb and a capacitor.

2.

Just after the switch is closed: what is the absolute value of the potential difference across the capacitor? Explain your reasoning.

3.

A long time after the switch is closed: what is the absolute value of the potential difference across the capacitor? Explain your reasoning.
When the capacitor is charging, the current through the resistor as a function of time is given by
\begin{equation*} I(t) = \frac{V_{bat}}{R}e^{-t/RC} \end{equation*}

4.

Given the result above, sketch a graph of the current through the resistor when the capacitor is charging. Describe how the graph would change if you were to increase the resistance of the circuit. Give a physical explanation for why you observe this change.