Blog 12: Radio Physics

Just the other day I was at my mom's office doing my homework when I glanced at her ancient radio that she has had forever. I've never paid much attention, but then I realized there is a lot of physics involving the old radio. Unlike most radios now days, this radio shows that the FM frequencies are in megahertz and the AM frequencies are in kilohertz. Before I didn't understand how radio stations were able to broadcast their programs and music, but now I know that they send the sound through specific frequencies. Whenever we change the tuning of the radio to the station we want to listen to, we allow the sound waves of that frequency to enter the radio and be played out by the speakers. The sound waves enter the radio through the antenna and then the radio distinguishes the information and sends it out through the speakers.

Blog 11: Phone Physics

When I was in 4th grade, I used to play with other people's cell phones all the time. I went from playing snake or bowling to playing Mary Had a Little Lamb with the keypad numbers. This past week I realized that I could play this song or Hot Cross Buns because each key in a row had a different frequency, so some were higher than the rest. For example, 1, 4, 7, and * have the highest tones, then 2, 5, 8 and 0 and 3, 6, 9, and # have the lowest tones. Since 1, 4, 7, and * are higher in tone, they have the highest frequency, while 3, 6, 9, and # have lower frequencies. Unlike a piano where when you hold down a key, there is a consistent sound made, but when I hold down a phone key it only makes one beep. This means that the period is very short because not much time is needed to make one vibration. Also I remember on the old Nokia phones, there used to be an application where you could make your own ringtone. Each key would be a different note and you could compose a song with all the keys. In this case, every key had a different frequency.