WEBVTT 1 00:00:00.000 --> 00:00:24.240 [unclear opening audio] 2 00:00:35.860 --> 00:00:36.940 Hi, Ladyada. 3 00:00:37.160 --> 00:00:38.520 Oh, hey, Adabot. What's up? 4 00:00:38.940 --> 00:00:42.660 I was wondering, why do radio stations each have their own number? 5 00:00:43.080 --> 00:00:48.120 Oh, the number of a radio station is the frequency on which it transmits. 6 00:00:48.380 --> 00:00:50.700 What is this frequency you speak of? 7 00:00:51.700 --> 00:00:56.160 Well, frequency is how often something happens, like, per second. 8 00:00:56.720 --> 00:00:57.000 Huh. 9 00:00:57.760 --> 00:00:58.260 Oh. 10 00:00:58.600 --> 00:01:03.100 Um, you know, to explain it, I better use my trusty oscilloscope here. 11 00:01:03.420 --> 00:01:06.500 Only thing is, I gotta get the probes, so I'll be right back. 12 00:01:07.560 --> 00:01:08.640 Okay, wait here. 13 00:01:10.760 --> 00:01:11.320 Psst. 14 00:01:11.500 --> 00:01:13.000 Hey, over here. 15 00:01:13.340 --> 00:01:13.680 What? 16 00:01:13.920 --> 00:01:14.680 Who said that? 17 00:01:15.400 --> 00:01:15.960 Me. 18 00:01:16.240 --> 00:01:17.820 The talking screen over here? 19 00:01:18.700 --> 00:01:20.260 Oh, hello, talking screen. 20 00:01:20.700 --> 00:01:25.520 I'm not just a screen, I'm an oscilloscope, and I can tell you quite a bit about 21 00:01:25.520 --> 00:01:26.160 frequency. 22 00:01:26.580 --> 00:01:27.600 Really? Like what? 23 00:01:28.100 --> 00:01:34.020 Well, like Ladyada was saying, frequency is how often something happens over time. 24 00:01:34.580 --> 00:01:37.820 And we measure frequency in units called hertz. 25 00:01:38.960 --> 00:01:40.940 Oh, does frequency hurt? 26 00:01:41.280 --> 00:01:43.600 Oh no, that's a totally different word. 27 00:01:44.500 --> 00:01:45.200 Oh good. 28 00:01:45.200 --> 00:01:50.900 Hertz is spelled H-E-R-T-Z, and it tells us how many times 29 00:01:50.900 --> 00:01:52.480 something happens per second. 30 00:01:53.600 --> 00:01:54.280 Okay. 31 00:01:55.080 --> 00:01:55.920 Watch this. 32 00:01:57.900 --> 00:02:03.760 Right now, my screen is flashing once per second, so we can say it is flashing at 33 00:02:03.760 --> 00:02:06.000 a frequency of one hertz. 34 00:02:09.440 --> 00:02:15.520 now my screen is flashing a bit faster three times per second which is a 35 00:02:15.520 --> 00:02:21.500 frequency of three Hertz means how many times 36 00:02:21.500 --> 00:02:25.080 per second precisely so why is 37 00:02:25.080 --> 00:02:31.160 frequency important for radio stations good question you see a radio station 38 00:02:31.160 --> 00:02:35.960 uses a large antenna to send out waves of electromagnetic energy. 39 00:02:37.160 --> 00:02:38.580 We call these 40 00:02:38.580 --> 00:02:44.340 radio waves. Each station broadcasts 41 00:02:44.340 --> 00:02:47.280 at its own special frequency, so they don't 42 00:02:47.280 --> 00:02:53.080 get confused with another station. So, for example, 43 00:02:53.420 --> 00:02:55.640 when you tune your radio to 44 00:02:55.640 --> 00:03:01.420 93.9, you're telling it to only receive radio 45 00:03:01.420 --> 00:03:06.820 waves, which have a frequency of 93.9 million 46 00:03:06.820 --> 00:03:12.280 hertz. Your radio then converts those radio waves into 47 00:03:12.280 --> 00:03:14.840 sound, so you can hear the station, 48 00:03:14.840 --> 00:03:17.840 which broadcasts at that particular frequency. 49 00:03:18.300 --> 00:03:21.540 This is 93.9 WBOT, the bot. 50 00:03:24.300 --> 00:03:29.280 all that happens so I can hear music yes it does amazing 51 00:03:29.280 --> 00:03:32.240 indeed and frequency is 52 00:03:32.240 --> 00:03:38.220 important for audio as well like sound waves from a speaker exactly 53 00:03:38.220 --> 00:03:39.940 a sound 54 00:03:39.940 --> 00:03:45.660 wave is a vibration moving through the air and the frequency of a sound wave 55 00:03:45.660 --> 00:03:52.280 determines the pitch of that sound a slow-moving or low-frequency 56 00:03:52.280 --> 00:03:53.660 wave sounds 57 00:03:53.660 --> 00:04:00.220 low-pitched and bassy and a fast-moving high-frequency 58 00:04:00.220 --> 00:04:02.260 wave has a much higher 59 00:04:05.040 --> 00:04:05.560 pitch. 60 00:04:06.380 --> 00:04:08.060 So slow waves sound low 61 00:04:08.060 --> 00:04:09.640 and fast waves sound high? 62 00:04:10.200 --> 00:04:12.040 That's right. Found them! 63 00:04:12.720 --> 00:04:13.980 Oop, someone's coming. 64 00:04:14.220 --> 00:04:15.980 I've got to go. Take care, 65 00:04:16.100 --> 00:04:17.520 Adabot, and stay curious. 66 00:04:18.520 --> 00:04:19.640 Thank you, oscilloscope. 67 00:04:19.880 --> 00:04:20.540 I will. 68 00:04:21.960 --> 00:04:24.100 Okay, I found my oscilloscope 69 00:04:24.100 --> 00:04:26.020 probe. Sorry it took me so long, but now 70 00:04:26.020 --> 00:04:28.140 I'm going to hook them up to my oscilloscope here 71 00:04:28.140 --> 00:04:30.100 and I'm going to be able to teach you all 72 00:04:30.100 --> 00:04:31.220 about frequency. 73 00:04:31.840 --> 00:04:34.380 No need, Ladyada. It all makes sense now. 74 00:04:34.620 --> 00:04:34.880 Really? 75 00:04:35.700 --> 00:04:39.880 Eh-eh-eh-eh. Frequency is how often something happens over time. 76 00:04:40.260 --> 00:04:45.400 Frequency helps us tune into radio waves or create a sound wave at a certain pitch. 77 00:04:45.640 --> 00:04:49.160 Wow, you do know a lot about frequency. Where'd you learn all of that? 78 00:04:49.340 --> 00:04:52.380 Well, my friend the oscilloscope taught me a lot. 79 00:04:53.980 --> 00:04:57.080 Uh, hey, oscilloscope, you okay in there?