What determines an inductor's inductance?

Inductance depends on: number of turns squared (N²), core material permeability (μ), cross-sectional area (A), and length (l). L = μN²A/l. Ferrite or iron cores dramatically increase inductance compared to air cores.

Why do inductors oppose current changes?

Changing current creates a changing magnetic field, which induces a voltage opposing the change (Lenz's law). This back-EMF resists current increase and sustains current during decrease. It's like inertia for electrical current—inductors resist any change in current flow.

What is mutual inductance?

When two inductors share magnetic flux, changing current in one induces voltage in the other—this is mutual inductance, measured in henrys. Transformers use this principle. Mutual inductance M relates to coupling coefficient k: M = k√(L₁L₂).

Why do PCB traces have inductance?

Any conductor carrying current creates a magnetic field, giving it inductance. A straight wire has about 1 nH per mm length. At high frequencies (100+ MHz), even short traces act as significant inductors. This parasitic inductance affects signal integrity and must be considered in RF design.

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About Inductance Conversion

Inductance measures a component's tendency to oppose changes in current by storing energy in a magnetic field. When current through an inductor changes, it generates a voltage that resists that change—this is electromagnetic induction, described by Faraday's law. The induced voltage V = L(di/dt) is proportional to both inductance and rate of current change. This property makes inductors act like electrical inertia, smoothing current variations in power supplies and blocking high-frequency signals while passing DC.

The SI単位 is the henry (H), defined as the inductance producing 1 volt when current changes at 1 ampere per second. Named after Joseph Henry who discovered self-inductance independently of Faraday. Inductors are essential in switching power supplies (storing energy between switching cycles), RF filters (frequency-selective circuits), transformers (coupling between windings via mutual inductance), and motors (creating rotating magnetic fields).

Our converter handles all standard inductance units used in electronics, power systems, and electrical engineering.

Common Inductance Conversions

変換元	変換先	乗数
H	mH	1,000
mH	H	0.001
H	μH	10⁶
μH	H	10⁻⁶
mH	μH	1,000
μH	mH	0.001
μH	nH	1,000
nH	μH	0.001
H	nH	10⁹

Inductance 単位リファレンス

Henry (H) – The SI単位, producing 1 volt when current changes at 1 ampere per second. Named after American scientist Joseph Henry who discovered self-inductance in 1831. One henry is relatively large—achieving it requires many turns of wire around a high-permeability core. Large power transformers and filter chokes reach several henrys. Primary windings of mains transformers typically measure 1-100 H.

Millihenry (mH) – 10⁻³ H, common in audio and power applications. Speaker crossover inductors: 0.1-10 mH. Power supply chokes and filter inductors: 1-100 mH. Relay coils and solenoids: 10-500 mH. Motor windings typically fall in this range. Wirewound inductors with ferrite or iron cores achieve millihenry values in practical sizes.

Microhenry (μH) – 10⁻⁶ H, the workhorse unit for power electronics and RF circuits. Switching power supply inductors: 1-1000 μH depending on frequency and power level. EMI filter chokes: 10-100 μH. AM radio antennas: 100-500 μH. Higher frequencies require lower inductance—MHz-range circuits use single-digit to tens of microhenrys.

Nanohenry (nH) – 10⁻⁹ H, essential for high-frequency RF and microwave work. GHz-range matching networks use 1-100 nH inductors. Chip inductors for wireless applications: 1-100 nH. Critically, every conductor has parasitic inductance—approximately 1 nH per millimeter of wire or trace length, which significantly impacts GHz circuit design.