0:00:00.490,0:00:02.290 - [Narrator] We've already[br]learned a lot about waves 0:00:02.290,0:00:04.740 and now we're going to connected[br]to the bit to technology, 0:00:04.740,0:00:06.640 especially the technology that most of us 0:00:06.640,0:00:09.630 use most frequently and[br]that's our cell phone. 0:00:09.630,0:00:12.730 So pause this video and[br]think if you can list 0:00:12.730,0:00:15.160 all of the waves that your cell phone 0:00:15.160,0:00:19.453 has to utilize or deal[br]with or generate waves. 0:00:21.690,0:00:25.040 All right, so the first[br]thing that some of you 0:00:25.040,0:00:27.890 might have realized is[br]that your cell phone 0:00:27.890,0:00:30.930 has to deal with sound waves. 0:00:30.930,0:00:34.250 So you have sound[br]traveling through the air. 0:00:34.250,0:00:37.720 Your phone has to detect that sound. 0:00:37.720,0:00:41.370 And then in most cases, it[br]needs to digitize that sound. 0:00:41.370,0:00:43.860 And we did other videos[br]where we talked about 0:00:43.860,0:00:46.360 sampling sound waves so[br]that you can store it 0:00:46.360,0:00:48.240 as digital information. 0:00:48.240,0:00:49.820 And then depending what's happening, 0:00:49.820,0:00:52.400 that detection is going to[br]happen with your microphone. 0:00:52.400,0:00:54.260 And if you were recording something, 0:00:54.260,0:00:57.180 say recording a video or[br]recording an audio file 0:00:57.180,0:01:00.100 that digitize sound wave[br]would then be stored. 0:01:00.100,0:01:01.970 And then if you wanted to play it back, 0:01:01.970,0:01:04.780 it would have to be turned[br]back into a sound wave, 0:01:04.780,0:01:08.080 which could then be[br]emitted by your microphone. 0:01:08.080,0:01:10.130 Now, it could also be that you're on, 0:01:10.130,0:01:12.740 let's say a video call or you are having 0:01:12.740,0:01:15.830 an actual phone call, the[br]original purpose of phones. 0:01:15.830,0:01:18.450 And so then that digitized information 0:01:18.450,0:01:23.200 is going to be transmitted to a cell tower 0:01:23.200,0:01:25.560 that could be tens of miles away. 0:01:25.560,0:01:28.130 And I always find that[br]amazing because the cell phone 0:01:28.130,0:01:31.350 really has, it doesn't transmit[br]in a particular direction, 0:01:31.350,0:01:33.810 it kind of transmits in every direction. 0:01:33.810,0:01:36.670 So it's got to be pretty powerful[br]to get to that cell tower 0:01:36.670,0:01:40.230 that might be around five or[br]10 or even more miles away. 0:01:40.230,0:01:42.620 And then of course, if[br]you're having a conversation, 0:01:42.620,0:01:45.880 that cell tower is transmitting[br]electromagnetic waves 0:01:45.880,0:01:47.470 in a bunch of different directions. 0:01:47.470,0:01:48.767 And then this cell phone says, 0:01:48.767,0:01:50.680 "Hey, that's the signal for me." 0:01:50.680,0:01:52.950 And it can take that digital information. 0:01:52.950,0:01:56.610 And then it could use that[br]to generate a wave pattern, 0:01:56.610,0:01:58.600 which is then emitted[br]by the microphone again, 0:01:58.600,0:02:00.410 which you'd then hear. 0:02:00.410,0:02:04.390 So sound waves is clearly a[br]big part of what's going on 0:02:04.390,0:02:07.010 with a lot of technology, not[br]just cell phones, obviously. 0:02:07.010,0:02:09.160 If you have a stereo system,[br]if you have a television, 0:02:09.160,0:02:11.650 sound waves are heavily utilized, 0:02:11.650,0:02:13.590 or at least you have to deal with them. 0:02:13.590,0:02:15.890 Now, what other type of wave? 0:02:15.890,0:02:17.990 Well, you might be saying light waves, 0:02:17.990,0:02:19.590 which would be correct, 0:02:19.590,0:02:21.770 but I'm gonna generalize[br]a little bit more and say, 0:02:21.770,0:02:26.370 electromagnetic waves of which light waves 0:02:26.370,0:02:28.950 are a type of electromagnetic waves. 0:02:28.950,0:02:31.400 How do you use light waves? 0:02:31.400,0:02:34.910 Well, a modern smartphone or[br]cell phone will have a camera. 0:02:34.910,0:02:39.730 And so it needs a way[br]to detect light waves. 0:02:39.730,0:02:43.300 So it will detect them and[br]once again, it will digitize, 0:02:43.300,0:02:45.560 it will store and then of course, 0:02:45.560,0:02:47.810 it has this nice big screen here. 0:02:47.810,0:02:50.430 So it needs a way to take[br]that digitized information 0:02:50.430,0:02:52.550 and then generate light waves. 0:02:52.550,0:02:56.210 Every pixel on the screen can[br]generate different frequencies 0:02:56.210,0:02:58.650 of light waves or at least[br]give the appearance altogether 0:02:58.650,0:03:02.320 of generating different[br]frequencies of light waves. 0:03:02.320,0:03:04.300 Now, light waves are not the only type 0:03:04.300,0:03:05.940 of electromagnetic wave. 0:03:05.940,0:03:09.230 We've talked about having to[br]communicate with a cell tower 0:03:09.230,0:03:13.320 that could be 5, 10, 15,[br]even further miles away. 0:03:13.320,0:03:15.480 Well, those waves it's using to connect 0:03:15.480,0:03:18.940 with your cell tower,[br]those are radio waves, 0:03:18.940,0:03:21.980 which are another type[br]of electromagnetic waves. 0:03:21.980,0:03:23.650 Now, are we done? 0:03:23.650,0:03:25.870 Well just to make sure we can[br]look at this little key here 0:03:25.870,0:03:27.520 that you see at the top of a cell phone, 0:03:27.520,0:03:30.060 and you could see that[br]cell signal that tells you 0:03:30.060,0:03:32.870 how good of a radio signal it is getting 0:03:32.870,0:03:35.200 from the cell tower, 0:03:35.200,0:03:38.070 but you can also see[br]this Wi-Fi signal here. 0:03:38.070,0:03:42.140 So Wi-Fi uses different[br]frequencies of radio waves 0:03:42.140,0:03:45.990 to communicate with the local[br]network wherever you are. 0:03:45.990,0:03:49.160 But once again, that is more radio waves. 0:03:49.160,0:03:50.460 So I will let you go. 0:03:50.460,0:03:53.010 I encourage you as you[br]learn anything in any topic. 0:03:53.010,0:03:54.410 Always look at the world around you 0:03:54.410,0:03:57.260 and see how these concepts[br]that you're learning in school 0:03:57.260,0:03:59.620 or that you're learning[br]in, say a Physics class 0:03:59.620,0:04:02.553 are connected to things you[br]do every moment of your life.