# How does the microwave know the popcorn is ready? **URL:** \ **Category:** Factual Questions\ **Created:** [December 9, 2005, 9:42pm UTC](https://boards.straightdope.com/t/how-does-the-microwave-know-the-popcorn-is-ready/334946 "2005-12-09T21:42:41Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Ca3799](https://avatars.discourse-cdn.com/v4/letter/c/9f8e36/32.png) [@Ca3799](https://boards.straightdope.com/u/Ca3799)\ **Post date:** [December 9, 2005, 9:42pm UTC](https://boards.straightdope.com/t/how-does-the-microwave-know-the-popcorn-is-ready/334946/1 "2005-12-09T21:42:41Z")
How does the microwave know the popcorn is ready? It also has settings for “casserole”, “pizza”, “fresh vegetable” , “frozen vegetable”, “auto defrost”, and “hold warm” etc. What a smart machine! ---
**Author:** ![Zsofia](https://avatars.discourse-cdn.com/v4/letter/z/7bcc69/32.png) [@Zsofia](https://boards.straightdope.com/u/Zsofia)\ **Post date:** [December 9, 2005, 9:44pm UTC](https://boards.straightdope.com/t/how-does-the-microwave-know-the-popcorn-is-ready/334946/2 "2005-12-09T21:44:45Z")
It doesn’t. It guesses at how long the popcorn takes. Mine has it so if it’s wrong you can adjust when the “microwave thinks it’s ready” - make “popcorn” mean shorter or longer. Assuming I haven’t been whooshed here. ---
**Author:** ![Ca3799](https://avatars.discourse-cdn.com/v4/letter/c/9f8e36/32.png) [@Ca3799](https://boards.straightdope.com/u/Ca3799)\ **Post date:** [December 9, 2005, 9:53pm UTC](https://boards.straightdope.com/t/how-does-the-microwave-know-the-popcorn-is-ready/334946/3 "2005-12-09T21:53:14Z")
Well, it says “sensor cook” on the box and lights up the word “sensor” when I push the popcorn button, but there doesn’t seem to be any kind of sensor attachment in there anywhere. The machine is not lying to me about having some kind of fancy sensor, is it? ---
**Author:** ![asterion](https://avatars.discourse-cdn.com/v4/letter/a/4da419/32.png) [@asterion](https://boards.straightdope.com/u/asterion)\ **Post date:** [December 9, 2005, 10:03pm UTC](https://boards.straightdope.com/t/how-does-the-microwave-know-the-popcorn-is-ready/334946/4 "2005-12-09T22:03:55Z")
As I understand my microwave, the settings have been optimized for an average bag of popcorn (or whatever else it’s got settings for) by the manufacturer. So, if the manufacturer’s calculations (and presumably tests) say that an x-size bag of popcorn has ultimate popping with no burned kernels at 2 minutes and 20 seconds at y-power level, the button sets the microwave to those settings. It also works really well–I’ve never burned a bag using those settings as long as I was making a full-size bag of popcorn and not one of those little single-person bags. ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [December 9, 2005, 10:09pm UTC](https://boards.straightdope.com/t/how-does-the-microwave-know-the-popcorn-is-ready/334946/5 "2005-12-09T22:09:18Z")
The oven has a humidity sensor. It monitors the humidity levels in the cavity, and when they reach a preset level depending on the food selection button you pressed, it knows the product is ready. The manufacturer programmed in the levels based on lab tests with typical samples of various types of food, and presumably averaged them out to determine the proper level. ---
**Author:** ![carnivorousplant](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnivorousplant/32/3563_2.png) [@carnivorousplant](https://boards.straightdope.com/u/carnivorousplant)\ **Post date:** [December 9, 2005, 10:12pm UTC](https://boards.straightdope.com/t/how-does-the-microwave-know-the-popcorn-is-ready/334946/6 "2005-12-09T22:12:11Z")
> [@Ca3799](#): > > The machine is not lying to me about having some kind of fancy sensor, is it? There are tiny little men in tin foil suits called “Sensors” who periodically check on the popcorn. ---
**Author:** ![Jayrot](https://avatars.discourse-cdn.com/v4/letter/j/3ec8ea/32.png) [@Jayrot](https://boards.straightdope.com/u/Jayrot)\ **Post date:** [December 9, 2005, 10:14pm UTC](https://boards.straightdope.com/t/how-does-the-microwave-know-the-popcorn-is-ready/334946/7 "2005-12-09T22:14:35Z")
> [@Q.E.D.](#): > > The oven has a humidity sensor. It monitors the humidity levels in the cavity, and when they reach a preset level depending on the food selection button you pressed, it knows the product is ready. The manufacturer programmed in the levels based on lab tests with typical samples of various types of food, and presumably averaged them out to determine the proper level. [“Accepted answer!”](http://boards.straightdope.com/sdmb/showthread.php?t=345859) 😃😃 ---
**Author:** ![Leviosaurus](https://avatars.discourse-cdn.com/v4/letter/l/439d5e/32.png) [@Leviosaurus](https://boards.straightdope.com/u/Leviosaurus)\ **Post date:** [December 9, 2005, 10:40pm UTC](https://boards.straightdope.com/t/how-does-the-microwave-know-the-popcorn-is-ready/334946/8 "2005-12-09T22:40:53Z")
> [@carnivorousplant](#): > > There are tiny little men in tin foil suits called “Sensors” who periodically check on the popcorn. Thanks for explaining it in terms I can understand! I hope the little man in my computer who actually posts this message does it correctly and doesn’t include any spelling errros. ---
**Author:** ![Bryan\_Ekers](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bryan_ekers/32/183_2.png) [@Bryan\_Ekers](https://boards.straightdope.com/u/Bryan_Ekers)\ **Post date:** [December 9, 2005, 10:55pm UTC](https://boards.straightdope.com/t/how-does-the-microwave-know-the-popcorn-is-ready/334946/9 "2005-12-09T22:55:18Z")
> [@carnivorousplant](#): > > There are tiny little men in tin foil suits called “Sensors” who periodically check on the popcorn. Are they related to the tiny men in fur coats that turn off the light in the fridge? ---
**Author:** ![ltfire](https://avatars.discourse-cdn.com/v4/letter/l/7ea924/32.png) [@ltfire](https://boards.straightdope.com/u/ltfire)\ **Post date:** [December 10, 2005, 12:39am UTC](https://boards.straightdope.com/t/how-does-the-microwave-know-the-popcorn-is-ready/334946/10 "2005-12-10T00:39:38Z")
> [@Bryan Ekers](#): > > Are they related to the tiny men in fur coats that turn off the light in the fridge? The real question is ‘doe’s the light actually go out?’ Go check. ---
**Author:** ![carnivorousplant](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnivorousplant/32/3563_2.png) [@carnivorousplant](https://boards.straightdope.com/u/carnivorousplant)\ **Post date:** [December 10, 2005, 12:53am UTC](https://boards.straightdope.com/t/how-does-the-microwave-know-the-popcorn-is-ready/334946/11 "2005-12-10T00:53:32Z")
> [@Leviosaurus](#): > > I hope the little man in my computer who actually posts this message does it correctly and doesn’t include any spelling errros. There is a labor dispute over the emmigration of Greek Sensors. ---
**Author:** ![Ike\_Witt](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ike_witt/32/283_2.png) [@Ike\_Witt](https://boards.straightdope.com/u/Ike_Witt)\ **Post date:** [December 10, 2005, 1:00am UTC](https://boards.straightdope.com/t/how-does-the-microwave-know-the-popcorn-is-ready/334946/12 "2005-12-10T01:00:17Z")
> [@carnivorousplant](#): > > There are tiny little men in tin foil suits called “Sensors” who periodically check on the popcorn. Wouldn’t there be arcing all over the place if they were wearing foil? ---
**Author:** ![Manduck](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/manduck/32/256_2.png) [@Manduck](https://boards.straightdope.com/u/Manduck)\ **Post date:** [December 10, 2005, 1:01am UTC](https://boards.straightdope.com/t/how-does-the-microwave-know-the-popcorn-is-ready/334946/13 "2005-12-10T01:01:29Z")
> [@ltfire](#): > > The real question is ‘doe’s the light actually go out?’ > > Go check. Yes it does. I know this because when I close the fridge door I can’t see the inside of the fridge anymore, therefore it must be dark in there, therefore the light is out. QED! ---
**Author:** ![jayjay](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jayjay/32/6765_2.png) [@jayjay](https://boards.straightdope.com/u/jayjay)\ **Post date:** [December 10, 2005, 1:13am UTC](https://boards.straightdope.com/t/how-does-the-microwave-know-the-popcorn-is-ready/334946/14 "2005-12-10T01:13:50Z")
When the popcorn is ready, the microwave will appear… ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [December 10, 2005, 1:16am UTC](https://boards.straightdope.com/t/how-does-the-microwave-know-the-popcorn-is-ready/334946/15 "2005-12-10T01:16:55Z")
> [@Manduck](#): > > QED! What? _What??_ ---
**Author:** ![carnivorousplant](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnivorousplant/32/3563_2.png) [@carnivorousplant](https://boards.straightdope.com/u/carnivorousplant)\ **Post date:** [December 10, 2005, 1:19am UTC](https://boards.straightdope.com/t/how-does-the-microwave-know-the-popcorn-is-ready/334946/16 "2005-12-10T01:19:33Z")
> [@adam yax](#): > > Wouldn’t there be arcing all over the place if they were wearing foil? Microwaves are on the order of centimeters, and the little Sensor people are only a few millimeters tall. :rolleyes: ---
**Author:** ![carnivorousplant](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnivorousplant/32/3563_2.png) [@carnivorousplant](https://boards.straightdope.com/u/carnivorousplant)\ **Post date:** [December 10, 2005, 1:59am UTC](https://boards.straightdope.com/t/how-does-the-microwave-know-the-popcorn-is-ready/334946/17 "2005-12-10T01:59:44Z")
> [@carnivorousplant](#): > > little Sensor people are only a few millimeters tall. Also, see the note above about inexpensive labor. ---
**Author:** ![Good\_Egg](https://avatars.discourse-cdn.com/v4/letter/g/96bed5/32.png) [@Good\_Egg](https://boards.straightdope.com/u/Good_Egg)\ **Post date:** [December 10, 2005, 3:09am UTC](https://boards.straightdope.com/t/how-does-the-microwave-know-the-popcorn-is-ready/334946/18 "2005-12-10T03:09:32Z")
> [@carnivorousplant](#): > > Microwaves are on the order of centimeters, and the little Sensor people are only a few millimeters tall. > > :rolleyes: Then they could easily be injured by bursting popcorn. Hope they have a union. ---
**Author:** ![carnivorousplant](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnivorousplant/32/3563_2.png) [@carnivorousplant](https://boards.straightdope.com/u/carnivorousplant)\ **Post date:** [December 10, 2005, 3:35am UTC](https://boards.straightdope.com/t/how-does-the-microwave-know-the-popcorn-is-ready/334946/19 "2005-12-10T03:35:10Z")
> [@Good Egg](#): > > Then they could easily be injured by bursting popcorn. Hope they have a union. They are quite agile, and it appears that you did not get the memo about cheap labor. ---
**Author:** ![asterion](https://avatars.discourse-cdn.com/v4/letter/a/4da419/32.png) [@asterion](https://boards.straightdope.com/u/asterion)\ **Post date:** [December 10, 2005, 3:36am UTC](https://boards.straightdope.com/t/how-does-the-microwave-know-the-popcorn-is-ready/334946/20 "2005-12-10T03:36:46Z")
> [@carnivorousplant](#): > > There are tiny little men in tin foil suits called “Sensors” who periodically check on the popcorn. Are they orange with green hair? [Next page](https://boards.straightdope.com/t/how-does-the-microwave-know-the-popcorn-is-ready/334946.md?page=2)