Home / Electronics / RL circuit and self-induction

RL circuit and self-induction

Watch coil current lag and measure the time constant using resistance and inductance.

    E09 · RL circuit and self-induction0.00 s · Ready

    Electronics · Capacitors and coils / Principles and inquiry

    RL circuit and self-induction experiment guide

    Watch coil current lag and measure the time constant using resistance and inductance.

    How does it work?

    τ = L/R; after one time constant the rising current reaches about 63.2% of its final value.

    Key relationship

    τ = L/R · I = (V/R)(1−e^(−t/τ))

    Try this investigation

    1. Watch coil current lag and measure the time constant using resistance and inductance.
    2. Run and record each of the three baseline presets.
    3. Compare the changed variable and its result with the baseline records.

    Interpreting your results

    During current rise in a 6 V, 20 Ω circuit, what is the current at t=τ?

    About 0.190 A

    Assumptions and limitations

    Coil resistance, parasitic capacitance and switch arcing are omitted. Experiment on screen; do not reproduce this with real power supplies, outlets or high voltage.