Exponential Decay (Time Constant)
Exponential decay toward a constant level, written with the time constant τ. Use it for RC and RL circuits, Newton’s law of cooling and other first-order decays where the time constant is the result you want.
Fit the example dataStart with your own data
Example: simulated voltage of a 22 µF capacitor discharging through 100 kΩ, 25 points with x and y uncertainties, opened as a new copy you can edit.
Parameters
- Value of y − C at x = 0.
- Time constant: the interval in x over which y − C falls by a factor of e, to about 37%. For an RC circuit, τ = RC.
- Constant level the decay approaches.
Tips
- τ and its uncertainty are reported directly. The half-life is τ ln 2; Exponential Decay (Half-life) fits it directly.
- This is the same curve as Exponential with Offset with b = −1/τ. A negative τ describes growth.
- For a charging capacitor, enter its voltage as y: A comes out negative, and C is the final voltage.
- Include data over several time constants so the level C is well determined.