Adabot: I was wondering … why does each radio station have its own number?

Adabot: What is this “frequency” you speak of?

Ladyada: Well … Frequency is the measurement of how often something happens.

Ladyada: Hmm - It might be easier to tell you about frequency … with the help of my oscilloscope here.

Ladyada: Just need to find my oscilloscope probes … I’ll be right back - wait here, ok?

Oscilloscope: *psst* - hey over here!

Oscilloscope: Me - the talking screen over here.

Oscilloscope: I’m not just a screen - I’m an oscilloscope! - and I could tell you quite a bit about frequency.

Oscilloscope: Well - like Ladyada was saying - frequency is how often something happens over time.  And we measure frequency in units called “Hertz”

Adabot: (troubled) Oh - does frequency hurt?

Oscilloscope: No, not at all!  That’s a totally different word :)

Oscilloscope: Hertz is spelled H-E-R-T-Z.  It tells us how many times something is happening per second.

Oscilloscope: Watch this -

Oscilloscope: Right now my screen is flashing once per second.  So we can say it is flashing at a *frequency* of one *hertz*.

Oscilloscope: Now my screen is flashing a bit faster - 3 times per second which is a frequency of three hertz.

Adabot: Got it - Hertz means - “how many times per second”!

Oscilloscope: Precisely!

Oscilloscope: Good question!

Oscilloscope: You see - a radio station uses a large antenna to send out waves of electromagnetic energy.  We call these “radio waves”.

Oscilloscope: Each station broadcasts at its own special frequency, so they don’t get confused with another station.

Oscilloscope: So when you tune your radio to 93.9, for example … you’re telling it to only receive radio waves which have a frequency of 93.9 million Hertz.  Your radio then converts those radio waves into sound, so you can hear the station which broadcasts at that particular frequency.

Adabot: Wow - all that happens so I can hear music?

Oscilloscope: Yes it does!

Oscilloscope: Indeed - and Frequency is also very important for audio as well.

Adabot: Audio - like the sound waves that come from the speaker?

Oscilloscope: Exactly.

Oscilloscope: You see - a sound wave is a vibration moving through the air.  And the frequency of a sound wave determines the pitch of that sound.

Oscilloscope: A slow moving or *low frequency* wave sounds low-pitched and bassy.

Oscilloscope: And a fast moving, *high frequency* wave has a much higher pitch.

Adabot: So slow waves sound low and fast waves sound high?

Oscilloscope: That’s right!

Oscilloscope: Oop - I think someone’s coming - gotta go!

Take care Adabot - stay curious!

Adabot: Frequency is how often something happens over time.  Knowing about frequency helps us tune into radio waves, or create sound waves at different pitches.