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Simple Definitions

The most important electronics terms, demystified in one place.


Our Take

Inductance could be thought of as the momentum of electricity. When electricity is flowing through something with high inductance, it doesn’t want to stop. It also doesn’t want to start flowing if it isn’t flowing yet. It creates a voltage to oppose the change in current flow, effectually fighting the change in current.

This yields some interesting results. With a high frequency signal, the electrons are changing direction very quickly, which is hard to do when there is high inductance, which is why inductors filter out high frequency waveforms. This is also why when you unplug your vacuum cleaner (or any appliance with a big motor) before turning it off with the switch, you get a large spark at the outlet. Motors have a very large inductance and the electricity wants to keep flowing when you unplug it. It generates extremely high voltages to maintain that current flow, which creates a spark. This is also why you need a flyback diode on motor drivers, so those voltages don’t destroy your electronics. Whew! As you can see, there’s a lot going on with inductance and that’s only scratching the surface.

Book Definition

The property whereby an inductor exhibits opposition to the charge of current flowing through it, measured in henrys (H).

Fundamentals of Electric Circuits, 5th Edition by Charles K. Alexander and Matthew N. O. Sadiku

Ability to produce induced voltage when cut by magnetic flux. Unit of inductance is the henry (H).

Grob’s Basic Electronics, 11th Edition by Mitchel E. Schultz

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