@KingDuken Ultrasonic sensors don't use electromagnetic waves for detection...

I had a 40W soldering iron bought a year ago. Despite light use it recently stopped working after being heated up for 45 mins. It didn't have any temperature control sort of thing. My question is that can it be due to over heating or something else?

@JRE Oops I meant sound waves lol duh. Ultrasonic -> Sound

@KingDuken Thanks a lot, I'll check out the book and these topics. Don't know about several of these things, definitely lots of gaps in my knowledge!