RC circuit

Definition

An RC circuit is a circuit composed of resistors (R) and capacitors (C) used to filter signals by frequency, store energy, or delay signals in electronic systems. The behavior of the circuit is characterized by the time constant $\tau = RC$.

5 Must Know Facts For Your Next Test

1. The time constant $\tau = RC$ determines how quickly a capacitor charges or discharges in an RC circuit.
2. In an RC charging circuit, the voltage across the capacitor increases exponentially with a time constant $\tau$.
3. In an RC discharging circuit, the voltage across the capacitor decreases exponentially with a time constant $\tau$.
4. At $t = \tau$, the voltage across a charging capacitor reaches approximately 63% of its final value.
5. The impedance of an RC circuit varies with frequency, making it useful for filtering applications.

Review Questions

• What does the time constant $\tau$ represent in an RC circuit?
• How does the voltage across a capacitor change over time when charging and discharging in an RC circuit?
• Why are RC circuits commonly used in signal filtering?

Related terms

Capacitor: A component that stores electrical energy in an electric field and resists changes in voltage.

Resistor: A component that resists the flow of electrical current, causing a drop in voltage.

$V = V_0 e^{-t/RC}$: $V = V_0 e^{-t/RC}$ describes how voltage decays over time during discharge in an RC circuit.