Electro Magnetic facts

While investigating facts about Electromagnetic Spectrum and Electromagnetic Waves, I found out little known, but curios details like:

To refine uranium for the nuclear bomb dropped on Hiroshima, huge coils for electro magnets were needed, and when people in charge couldn't find enough copper, because of the war, a creative solution was provided and tons of silver were borrowed from the USA national treasury to make them.

how electromagnetic waves are produced?

France and Germany are jointly working on Electro-Magnetic Railguns since 1987, and have build an EM artillery truck in 1997, or 10 years before the USA started their researchs about it

What electromagnetic wave has the longest wavelength?

In my opinion, it is useful to put together a list of the most interesting details from trusted sources that I've come across answering what electromagnetic spectrum. Here are 2 of the best facts about Electromagnetic Radiation and Electromagnetic Induction I managed to collect.

what electromagnetic wave has the highest frequency?