1 00:00:00,000 --> 00:00:05,040 Hey, how do microwave ovens work? And more importantly, how do the microwaves 2 00:00:05,040 --> 00:00:09,040 stay in the microwave? The simple explanation is that microwaves 3 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. 4 00:00:13,040 --> 00:00:16,920 So let's dig a little deeper into this hot pocket of science. 5 00:00:17,920 --> 00:00:22,240 Microwave radiation has several key properties that make it useful for cooking. 6 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, 7 00:00:27,040 --> 00:00:32,000 non-ionizing radiation. Like radio waves, infrared, and visible light. 8 00:00:32,000 --> 00:00:37,120 This is opposed to dangerous, high-energy, ionizing radiation like X-rays and gamma rays 9 00:00:37,120 --> 00:00:41,360 that have a relatively high chance of damaging DNA and causing cancer 10 00:00:41,360 --> 00:00:45,160 and a small chance of transforming you into a giant green rage monster. 11 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 12 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 13 00:00:55,400 --> 00:00:59,520 and other physical damage, which is why it's important to keep them contained. 14 00:00:59,520 --> 00:01:02,600 Second, microwaves interact with polar molecules, 15 00:01:02,600 --> 00:01:06,120 which are made of both positively and negatively charged atoms, 16 00:01:06,120 --> 00:01:09,440 causing them to spin. The extra energy from the spinning 17 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 18 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. 19 00:01:20,240 --> 00:01:23,840 But microwaves don't interact much with other kinds of molecules. 20 00:01:23,840 --> 00:01:28,080 They really just bounce off them, meaning that microwaves can be easily contained 21 00:01:28,080 --> 00:01:31,200 by, say, a small closed metal box. 22 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. 23 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. 24 00:01:41,800 --> 00:01:45,040 Without the water molecules in food to absorb the microwaves, 25 00:01:45,040 --> 00:01:48,160 they can end up damaging the device's electronics over time. 26 00:01:48,160 --> 00:01:52,720 As for putting metal in the microwave, well, it won't make the device explode, 27 00:01:52,720 --> 00:01:58,040 but pointed metal objects might spark due to electric charge building up at the tips, 28 00:01:58,040 --> 00:02:01,960 which, incidentally, is also why Guy Fieri's hair always looked like that. 29 00:02:01,960 --> 00:02:05,760 But hey, what about that window? Electromagnetic radiation like radio waves 30 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 31 00:02:10,960 --> 00:02:14,680 when you look in the window is because they're essentially a kind of Faraday cage 32 00:02:14,680 --> 00:02:17,760 that blocks electromagnetic waves above a certain size 33 00:02:17,760 --> 00:02:20,840 from getting in or out. You've probably noticed that the window 34 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 35 00:02:25,520 --> 00:02:29,560 for visible light to escape, like a mouse darting out of an elephant pen, 36 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 37 00:02:35,040 --> 00:02:39,480 in the visible light spectrum, which are only around 400 to 700 nanometers long. 38 00:02:39,480 --> 00:02:44,580 The microwave spectrum is from a millimeter to 30 centimeters, or about 12 inches. 39 00:02:44,580 --> 00:02:48,220 Microwave ovens use a frequency around 2.45 gigahertz, 40 00:02:48,220 --> 00:02:51,580 which results in waves around 4.8 inches in size, 41 00:02:51,580 --> 00:02:55,800 which is way bigger than these holes. These are simply not microwave-shaped holes. 42 00:02:55,800 --> 00:03:00,200 A microwave oven is typically only unsafe if the door no longer seals, 43 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 44 00:03:04,400 --> 00:03:08,080 as an ammo-saving way to defend your compound in a zombie apocalypse. 45 00:03:08,080 --> 00:03:11,080 It's also an unsafe place to store elements like radium 46 00:03:11,080 --> 00:03:15,080 that emit gamma radiation, because gamma waves are small enough 47 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 48 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 49 00:03:23,480 --> 00:03:26,660 immediately after cooking. Microwaves travel extremely quickly, 50 00:03:26,660 --> 00:03:29,920 so they'll be absorbed into the food long before the door opens. 51 00:03:29,920 --> 00:03:33,720 Although waiting for a little bit does have the advantage of allowing any hot spots 52 00:03:33,720 --> 00:03:37,440 to dissipate more evenly throughout the food. But that's up to you, 53 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. 54 00:03:41,920 --> 00:03:45,600 I'm sorry. That was a Techquickie, and it's over now. Thanks for watching. 55 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, 56 00:03:49,080 --> 00:03:52,880 comment below with video suggestions, and don't forget to subscribe and follow. 57 00:03:52,880 --> 00:03:55,160 It'll make me happy. Maybe you too.