We went to a charity concert in the suburbs of Oxford at the weekend. It started with an interview with Colin Greenwood of Radiohead. I just wanted you to know that I had been in the same room as somebody famous! He came across as generous, witty and intelligent. He was there because he is an ambassador for the charity being supported by KOA this year: http://www.childrensradiofoundation.org/ I wanted to post about this, but how to get some Physics into my name dropping? I thought about doing colour filters with the stage lights. But I then thought that it might be good to start a series of posts about radio. Imagine the world without the harnessing of electromagnetic waves for communication by humans! We'd be back in 1850. Radio waves are very low frequency electromagnetic waves. You set up such a wave at a particular frequency and then you either vary its amplitude in time to the voice or music (this is AM) or you slightly vary the frequency in time to the voice or music (this is FM). The electromagnetic carrier wave has a varying electric field at 90 degrees to a varying magnetic field. To detect the waves, you either get the electric field to get electrons to wobble in a pole aerial, or you get the varying magnetic field to induce electricity in a magnetic coil aerial. Colin Greenwood is almost my age. He said how much he'd enjoyed radio for music as a child. It was the same with me. I still love radio more than video for music. More to follow.
