Home Back

Capacitor Formulas and Calculations

Charging Capacitor Voltage Formula:

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

volts
seconds
seconds

Unit Converter ▲

Unit Converter ▼

From: To:

1. What is the Capacitor Charging Voltage Formula?

The capacitor charging voltage formula describes how the voltage across a capacitor changes over time when charging through a resistor. It's a fundamental equation in RC circuit analysis and demonstrates exponential charging behavior.

2. How Does the Calculator Work?

The calculator uses the capacitor charging equation:

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

Where:

Explanation: The equation shows how the capacitor voltage asymptotically approaches the source voltage with a time constant that determines the charging rate.

3. Importance of Capacitor Voltage Calculation

Details: Understanding capacitor charging is essential for designing timing circuits, filters, power supplies, and many other electronic applications where controlled charging/discharging is needed.

4. Using the Calculator

Tips: Enter the source voltage (V₀), time (t) since charging began, and the circuit's time constant (τ). All values must be positive numbers with τ > 0.

5. Frequently Asked Questions (FAQ)

Q1: What happens when t = τ?
A: After one time constant (t = τ), the capacitor reaches about 63.2% of the source voltage.

Q2: How long does it take to fully charge?
A: Theoretically infinite time, but practically 5τ is considered full charge (99.3% of V₀).

Q3: What affects the time constant τ?
A: τ = R×C, so it depends on the resistance in the circuit and the capacitance value.

Q4: Can this be used for discharging?
A: For discharging, use V = V₀ × e^(-t/τ). The calculator can be modified for this case.

Q5: What units should be used?
A: Consistent units are essential - typically volts for voltage and seconds for time.

Capacitor Formulas and Calculations© - All Rights Reserved 2025