

Chuck Yeager’s Air Combat would ask for various airplane specs (“what is the service ceiling of an F-4E?,” “what is the ferry range of a MiG-15?”), and you had to flip through a booklet to find the answer.
You could copy the book, but it was fairly long so I guess the friction kept you in check.















High frequency is generally bad for transmission line losses, so getting power from A to B is better at lower frequency — DC is a great option here.
If we switched to DC, many things would still flicker though as they would presumably use switching power supplies, but those could be relatively high frequency like you said.
Interestingly, airplanes use 400Hz, as transmission over distance doesn’t matter, and transformers can be made much smaller/lighter.