The RL time constant controls a first-order inductive circuit’s exponential current response.
Difficulty
Intermediate
Read time
5 min
Prerequisites
Basic algebra, consistent units, and the stated model assumptions
Source
OpenStax, College Physics 2e, §23.10 (Paul Peter Urone and Roger Hinrichs)OpenFormulaGraph equation reference; FormuLab adaptation details and license are provided below.
Adapted from OpenFormulaGraph, under CC BY 4.0.
FormuLab adapted wording, notation, applicability conditions and topic placement, and expanded the numerical check into a worked example.
The RL time constant controls a first-order inductive circuit’s exponential current response. After one time constant, the remaining deviation from the final value is about 36.8%.
| Symbol | Meaning | Units |
|---|---|---|
| Time Constant | ||
| Inductance | ||
| Electrical Resistance |
Estimate a first-order RL response timescale.
Compare the effect of inductance and resistance.
An RL circuit has inductance 2.00 H and total resistance 4.00 Ω. Find its time constant.
OpenFormulaGraph equation reference; FormuLab adaptation details and license are provided below.
Adapted from OpenFormulaGraph, under CC BY 4.0.
FormuLab adapted wording, notation, applicability conditions and topic placement, and expanded the numerical check into a worked example.
Assumptions
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