Ah, the old 'Interviewer making an idiot of themselves' trick!
When I was being interviewed for my first job, as an electronics maintenance engineer for an oilfield-related company, I had made it into the 'second round', where they took you down to the lab and gave you some practical tests: can you solder? can you work a multimeter and scope? that kind of thing.
The lab supervisor handed me an open-frame module with lots of exposed parts, and asked me what I thought it might be.
It was clearly a simple linear power supply: A transformer, bridge rectifier, and some big caps.
I take hold of it *very* carefully.
"What voltage do you think it might produce?" he asks.
Looking at the voltage rating on the big caps, I see they are rated at something like 2000v.
So I guess "something between 1000 and 1500v or so".
Quite right.
I hand it back, and he grasps it carelessly.
Whomp! and is thrown back off his wheely chair into a snotty heap on the ground.
A suppressed grin and a raised eyebrow from me, and I have the job.