WEBVTT 00:00:00.000 --> 00:00:05.040 Hey, how do microwave ovens work? And more importantly, how do the microwaves 00:00:05.040 --> 00:00:09.040 stay in the microwave? The simple explanation is that microwaves 00:00:09.040 --> 00:00:13.040 are actually too big to get out of the oven. But we can do better than that. 00:00:13.040 --> 00:00:16.920 So let's dig a little deeper into this hot pocket of science. 00:00:17.920 --> 00:00:22.240 Microwave radiation has several key properties that make it useful for cooking. 00:00:22.240 --> 00:00:27.040 First, it's not too risky to use at home because it's a form of low-frequency, 00:00:27.040 --> 00:00:32.000 non-ionizing radiation. Like radio waves, infrared, and visible light. 00:00:32.000 --> 00:00:37.120 This is opposed to dangerous, high-energy, ionizing radiation like X-rays and gamma rays 00:00:37.120 --> 00:00:41.360 that have a relatively high chance of damaging DNA and causing cancer 00:00:41.360 --> 00:00:45.160 and a small chance of transforming you into a giant green rage monster. 00:00:45.160 --> 00:00:50.200 That's not to say that microwaves can't hurt you. After all, humans are much like hamburgers 00:00:50.200 --> 00:00:55.400 in the sense that we are both made of flesh. At high enough levels, microwaves can cause burns 00:00:55.400 --> 00:00:59.520 and other physical damage, which is why it's important to keep them contained. 00:00:59.520 --> 00:01:02.600 Second, microwaves interact with polar molecules, 00:01:02.600 --> 00:01:06.120 which are made of both positively and negatively charged atoms, 00:01:06.120 --> 00:01:09.440 causing them to spin. The extra energy from the spinning 00:01:09.440 --> 00:01:14.840 then radiates from the molecules as heat. In the case of food, these are typically water molecules 00:01:14.840 --> 00:01:20.240 where the oxygen atom has a positive charge while the two hydrogen atoms have a negative charge. 00:01:20.240 --> 00:01:23.840 But microwaves don't interact much with other kinds of molecules. 00:01:23.840 --> 00:01:28.080 They really just bounce off them, meaning that microwaves can be easily contained 00:01:28.080 --> 00:01:31.200 by, say, a small closed metal box. 00:01:31.200 --> 00:01:36.960 That's how microwaves heat just the food and not the surrounding air or the sides of the oven. 00:01:36.960 --> 00:01:41.800 This is also why it's not a good idea to run a microwave oven while it's empty. 00:01:41.800 --> 00:01:45.040 Without the water molecules in food to absorb the microwaves, 00:01:45.040 --> 00:01:48.160 they can end up damaging the device's electronics over time. 00:01:48.160 --> 00:01:52.720 As for putting metal in the microwave, well, it won't make the device explode, 00:01:52.720 --> 00:01:58.040 but pointed metal objects might spark due to electric charge building up at the tips, 00:01:58.040 --> 00:02:01.960 which, incidentally, is also why Guy Fieri's hair always looked like that. 00:02:01.960 --> 00:02:05.760 But hey, what about that window? Electromagnetic radiation like radio waves 00:02:05.760 --> 00:02:10.960 and microwaves can pass through glass, right? The reason why microwave ovens don't melt your face off 00:02:10.960 --> 00:02:14.680 when you look in the window is because they're essentially a kind of Faraday cage 00:02:14.680 --> 00:02:17.760 that blocks electromagnetic waves above a certain size 00:02:17.760 --> 00:02:20.840 from getting in or out. You've probably noticed that the window 00:02:20.840 --> 00:02:25.520 of a microwave door has a fine mesh embedded in it. Those holes are more than big enough 00:02:25.520 --> 00:02:29.560 for visible light to escape, like a mouse darting out of an elephant pen, 00:02:29.560 --> 00:02:35.040 but they're way too small for the microwaves to get through. Microwaves are quite a bit bigger than waves 00:02:35.040 --> 00:02:39.480 in the visible light spectrum, which are only around 400 to 700 nanometers long. 00:02:39.480 --> 00:02:44.580 The microwave spectrum is from a millimeter to 30 centimeters, or about 12 inches. 00:02:44.580 --> 00:02:48.220 Microwave ovens use a frequency around 2.45 gigahertz, 00:02:48.220 --> 00:02:51.580 which results in waves around 4.8 inches in size, 00:02:51.580 --> 00:02:55.800 which is way bigger than these holes. These are simply not microwave-shaped holes. 00:02:55.800 --> 00:03:00.200 A microwave oven is typically only unsafe if the door no longer seals, 00:03:00.200 --> 00:03:04.400 the device has a hole in it, or it has been modified to run with the door open 00:03:04.400 --> 00:03:08.080 as an ammo-saving way to defend your compound in a zombie apocalypse. 00:03:08.080 --> 00:03:11.080 It's also an unsafe place to store elements like radium 00:03:11.080 --> 00:03:15.080 that emit gamma radiation, because gamma waves are small enough 00:03:15.080 --> 00:03:19.160 to get through the holes in the door's mesh. I'm hoping that none of you are currently 00:03:19.160 --> 00:03:23.480 storing radium in the microwave, but if you are, please stop. And don't worry about opening the door 00:03:23.480 --> 00:03:26.660 immediately after cooking. Microwaves travel extremely quickly, 00:03:26.660 --> 00:03:29.920 so they'll be absorbed into the food long before the door opens. 00:03:29.920 --> 00:03:33.720 Although waiting for a little bit does have the advantage of allowing any hot spots 00:03:33.720 --> 00:03:37.440 to dissipate more evenly throughout the food. But that's up to you, 00:03:37.440 --> 00:03:41.920 and how much of an appetite you still have after I made you think about cooked zombies just now. 00:03:41.920 --> 00:03:45.600 I'm sorry. That was a Techquickie, and it's over now. Thanks for watching. 00:03:45.600 --> 00:03:49.080 Like the video if you liked it. Dislike it if you disliked it. Check out our other videos, 00:03:49.080 --> 00:03:52.880 comment below with video suggestions, and don't forget to subscribe and follow. 00:03:52.880 --> 00:03:55.160 It'll make me happy. Maybe you too.