What caused the shift from calling things like rheostats and condensers to resistors and capacitors, or the move from cycles to Hertz?
It seemed to just pop up out of nowhere, seeing as the previous terms seemed fine, and are in use for some things today (like rheostat brakes, or condenser microphones).
Rheostats are a type of variable resistor, commonly seen in the form of potentiometers.
“Condenser” came from the analogy of steam power’s condenser, which was a recent/new thing for steam engines around the same time people were starting with electricity. Language changed, though, because the analogy was imperfect.
Rheostats are two wire devices, think of them as current controlling. Potentiometers are three wire devices, typically used as voltage dividers. They are not the same.