The inductor: the coil that fights change
Why the current in a coil can't jump (it stores energy in a magnetic field), where the relay's turn-off spike comes from, and how inductors smooth current.
Meet the coil that fights change! 🌀⚡
1️⃣ WHAT IT IS: an inductor is just wire wound into a coil (often around a ferrite core). Current through it makes a magnetic field, and the coil stores energy in that field. Symbol: a row of loops. Unit: the henry (H).
2️⃣ SWITCH ON: change the current and the coil pushes back. So the current rises slowly, not at once.
3️⃣ SWITCH OFF: the current can't stop at once, so the coil makes a big voltage spike (V = L × ΔI ÷ Δt) — often 100+ V, enough to spark. A relay's coil does the same, that's why relays need a flyback diode across the coil.
📌 A coil hates change.
Read the voiceover (transcript)
- Meet the coil that fights change!
- An inductor is wire wound into a coil. Current through it makes a magnetic field.
- Change the current, and the coil pushes back. So the current rises slowly, not at once.
- Switch it off, and it fights again: a big voltage spike! That's why relays need a diode.
- A coil hates change!
- Next: the five-five-five timer! Follow for lesson twelve!
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