1. What is a Capacitor Discharge Calculator?

Definition: This calculator determines the remaining voltage across a capacitor after discharging through a resistor for a given time period.

Purpose: It helps electronics engineers, technicians, and hobbyists analyze RC circuits and capacitor behavior.

2. How Does the Calculator Work?

The calculator uses the exponential decay formula:

Where:

• \( V \) — Voltage at time t (volts)
• \( V_0 \) — Initial voltage (volts)
• \( t \) — Discharge time (seconds)
• \( R \) — Resistance (ohms)
• \( C \) — Capacitance (farads)

Explanation: The voltage decays exponentially with a time constant (τ = RC), where τ is the time for voltage to drop to ~37% of V₀.

3. Importance of Capacitor Discharge Calculation

Details: Understanding discharge characteristics is crucial for circuit design, timing applications, and safety considerations when working with charged capacitors.

4. Using the Calculator

Tips: Enter the initial capacitor voltage, discharge time, resistance value, and capacitance. All values must be positive (time can be zero).

5. Frequently Asked Questions (FAQ)

Q1: What is the time constant (RC) in a capacitor discharge?
A: The RC time constant (τ) is the time required for the voltage to drop to 36.8% (1/e) of its initial value.

Q2: How long does it take for a capacitor to fully discharge?
A: Technically, a capacitor never fully discharges, but after 5τ it's considered effectively discharged (~0.7% of V₀ remains).

Q3: Why does the voltage decay exponentially?
A: The discharge rate is proportional to the remaining voltage, creating a characteristic exponential curve.

Q4: How do I calculate the discharge time for a specific voltage?
A: Rearrange the formula: \( t = -RC \ln(V/V_0) \)

Q5: Does this apply to all capacitor types?
A: Yes, but real capacitors may have additional factors like leakage current that affect discharge.