Inductance Converter

The Magnetic Opposition: Inductance

In the trinity of passive electronic components—resistors, capacitors, and inductors—inductance is often considered the most complex to master. Inductance is the physical property of a conductor that opposes any change in the electric current flowing through it. It achieves this by storing energy in a magnetic field. Whenever current flows through a wire, a magnetic field expands around it. If the current suddenly drops, the magnetic field collapses, releasing its stored energy back into the wire as a voltage spike that tries to keep the current flowing.

This phenomenon, known as Lenz's Law, is the foundation of almost all modern power generation. It is the principle behind electric motors, transformers, radio antennas, and wireless phone chargers. Calculating the exact inductance of a coil is an absolute requirement for electrical engineers designing power supplies or tuning radio frequencies.

The Henry (H): The Unit of Magnetic Storage

The International System of Units (SI) measures inductance in the Henry (H), named after the American scientist Joseph Henry, who discovered electromagnetic induction independently of (and at the same time as) Michael Faraday. Mathematically, a circuit has an inductance of one Henry if a current changing at the rate of one Ampere per second induces a counter-electromotive force of one Volt.

Because a full Henry represents a massive magnetic field, you will only see components rated in whole Henrys in large-scale applications: industrial power grid transformers, massive electric car motors, and audio chokes in vintage vacuum tube amplifiers.

Millihenrys (mH) and Microhenrys (μH)

For modern digital electronics, the Henry is vastly too large. Engineers instead use Millihenrys (mH), Microhenrys (μH), and Nanohenrys (nH). When you open a computer power supply, the small copper coils wrapped around ferrite rings are inductors, typically rated between 10 μH and 100 μH. They are used to smooth out the power delivery, preventing sudden spikes of current from destroying the delicate microprocessors.

On an even smaller scale, Nanohenrys (nH) are used in radio frequency (RF) engineering. The microscopic inductors inside a smartphone's Wi-Fi antenna are tuned to exact Nanohenry values to resonate perfectly with a 2.4 GHz or 5 GHz radio wave.

The Dangers of Inductive Kickback

Converting inductance accurately is a critical safety parameter in circuit design. Because inductors fiercely oppose changes in current, suddenly flipping a switch to turn off a highly inductive load (like a large motor) will cause the collapsing magnetic field to generate thousands of Volts in a fraction of a second. This "inductive kickback" can blow up microcontrollers, destroy switches, and cause fatal electrocutions if the circuit isn't designed with proper protective diodes. Unitomatic's Inductance Converter allows engineers to perfectly translate magnetic field storage across the entire metric scale to ensure proper circuit protection.