|Karol Pollak electromagnetism
Karol Pollak invented the diode bridge also known as the Graetz bridge or the bridge rectifier. An arrangement of diodes that permit current in only one direction converts alternating current into direct current.
Leo Graetz popularized Pollak’s bridge and was German instead of Polish assuming that had anything to do with it.
My father once showed me one and I held it in my hand not as a component of a circuit but as a work of sculpture with a hidden purpose that was no longer needed.