RC Circuit Voltage Calculator

RC Circuit Voltage Equation:

\[ V = V_0 \times (1 - e^{-t / (R \times C)}) \]

Initial Voltage (V₀):

volts

Time (t):

seconds

Resistance (R):

ohms

Capacitance (C):

farads

Voltage (V):

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What is the RC Circuit Voltage Equation?

The RC circuit voltage equation calculates the voltage across a capacitor in a resistor-capacitor circuit during charging. It describes how the voltage increases over time when a DC voltage is applied to the circuit.

2. How Does the Calculator Work?

The calculator uses the RC circuit voltage equation:

\[ V = V_0 \times (1 - e^{-t / (R \times C)}) \]

Where:

\( V \) — Voltage across capacitor (volts)
\( V_0 \) — Initial voltage/source voltage (volts)
\( t \) — Time (seconds)
\( R \) — Resistance (ohms)
\( C \) — Capacitance (farads)
\( e \) — Euler's number (~2.71828)

Explanation: The equation shows how the capacitor voltage approaches the source voltage exponentially over time, with the time constant τ = R×C determining the charging rate.

3. Importance of RC Circuit Voltage Calculation

Details: Accurate voltage calculation is crucial for designing timing circuits, filters, signal processing systems, and understanding capacitor charging behavior in electronic circuits.

4. Using the Calculator

Tips: Enter initial voltage in volts, time in seconds, resistance in ohms, and capacitance in farads. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is the time constant (τ) in an RC circuit?
A: The time constant τ = R×C represents the time required for the voltage to reach approximately 63.2% of its final value.

Q2: How long does it take for a capacitor to fully charge?
A: A capacitor is considered fully charged after about 5 time constants (5τ), when it reaches over 99% of the source voltage.

Q3: What happens if resistance or capacitance is zero?
A: The equation becomes undefined as division by zero occurs. Both R and C must be positive values.

Q4: Can this equation be used for discharging circuits?
A: For discharging, the equation becomes V = V₀ × e^(-t/RC), where V₀ is the initial voltage.

Q5: What are typical units for capacitance in practical circuits?
A: While farads are the SI unit, practical circuits often use microfarads (μF = 10⁻⁶ F) or picofarads (pF = 10⁻¹² F).