Wikipedia Trail: From mobile phone to refraction

I just wrote a post about talking to a friend, so my first word I searched was phone. I wanted to learn more about the object that I spend a lot of my time on!
mobile phone

The next trail was the cellular network wikipedia page. I never know what Sprint or Verizon are talking about so I read up on cellular network. All it means is that the last link is wireless.
cellular network

The next page I went to was radio wave. This is so very interesting! There is an animation that really caught my eye. I did not know that the use of radio waves is regulated by the law.
radio wave

The last page I went to was refraction. This is a phenomenon that is easily explained by the conservation of energy. There are equations that show refraction.
refraction

refraction