Nils Gustaf Dalen, ""invention of automatic regulators for use in conjunction with gas accumulators for illuminating lighthouses and buoys".
I think the question here is if the discovery was really "physics" as such; although I guess that could be said for the integrated circuit as well.
Dahlen's system was used in countless lighthouses around the world for close of half a century and made automatic lighthouses much more practical. Hence, giving him the price was probably very much in the spirit of what Nobel.had in mind.
Also, the sun valve is a very, very clever invention.