# Can you actually reverse the polarity? **URL:** \ **Category:** Factual Questions\ **Created:** [March 2, 2011, 5:44pm UTC](https://boards.straightdope.com/t/can-you-actually-reverse-the-polarity/573235 "2011-03-02T17:44:47Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![Heyoka13](https://avatars.discourse-cdn.com/v4/letter/h/b9e5f3/32.png) [@Heyoka13](https://boards.straightdope.com/u/Heyoka13)\ **Post date:** [March 2, 2011, 7:20pm UTC](https://boards.straightdope.com/t/can-you-actually-reverse-the-polarity/573235/21 "2011-03-02T19:20:39Z")
> [@engineer\_comp\_geek](#): > > . . . Peltiers aren’t very efficient, but they are small and have no moving parts which makes them kinda cool and useful. Um, er, \*kinda cool,\*on one side. Love them puns, keep 'em coming! ---
**Author:** ![Crafter\_Man](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crafter_man/32/458_2.png) [@Crafter\_Man](https://boards.straightdope.com/u/Crafter_Man)\ **Post date:** [March 2, 2011, 7:21pm UTC](https://boards.straightdope.com/t/can-you-actually-reverse-the-polarity/573235/22 "2011-03-02T19:21:03Z")
> [@Chronos](#): > > For AC (e.g., things plugged into a wall socket) the device will work just fine plugged in either way, but many plugs have asymmetric prongs as a safety feature: If your house and lamp are wired properly, then the exposed part of the light socket will be the neutral (which under ordinary circumstances will probably not hurt you if you touch it), while the more dangerous hot contact will be down in the bottom of the socket, where it’s harder to accidentally touch it. Devices with power switches usually have polarized plugs, since you want to switch the hot and not the neutral. ---
**Author:** ![Crafter\_Man](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crafter_man/32/458_2.png) [@Crafter\_Man](https://boards.straightdope.com/u/Crafter_Man)\ **Post date:** [March 2, 2011, 7:24pm UTC](https://boards.straightdope.com/t/can-you-actually-reverse-the-polarity/573235/23 "2011-03-02T19:24:42Z")
> [@md2000](#): > > Overpower them with reverse voltage and you could damage them. Electronics, unlike motors, does not work “backwards”. Most electronics is tolerant enough of simple reverse voltage that it should survive, for example, putting batteries in backward. Of course, feed enough voltage/amps into anything and it will fail a smoke test - correct polarity, reverse, or AC. I once saw a design that used a full-wave bridge rectifier after the battery. I guess the designers were worried about damaged caused by reverse polarity. While this approach would work, it’s certainly not very efficient. ---
**Author:** ![The\_Hamster\_King](https://avatars.discourse-cdn.com/v4/letter/t/8edcca/32.png) [@The\_Hamster\_King](https://boards.straightdope.com/u/The_Hamster_King)\ **Post date:** [March 2, 2011, 7:29pm UTC](https://boards.straightdope.com/t/can-you-actually-reverse-the-polarity/573235/24 "2011-03-02T19:29:20Z")
> [@Chefguy](#): > > The flux capacitor won’t allow you to do that. That’s why you should use an oscillation overthruster instead. ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [March 2, 2011, 7:31pm UTC](https://boards.straightdope.com/t/can-you-actually-reverse-the-polarity/573235/25 "2011-03-02T19:31:55Z")
> [@Chronos](#): > > One of my favorite SDMB posts ever was someone saying that he plugged a lamp in backwards, and it started emitting antiphotons. Or you could reverse the polarity of a microwave oven and make icecubes in 30 seconds. ---
**Author:** ![Chefguy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chefguy/32/138_2.png) [@Chefguy](https://boards.straightdope.com/u/Chefguy)\ **Post date:** [March 2, 2011, 11:36pm UTC](https://boards.straightdope.com/t/can-you-actually-reverse-the-polarity/573235/26 "2011-03-02T23:36:24Z")
> [@The\_Hamster\_King](#): > > That’s why you should use an oscillation overthruster instead. Now that’s just silly. ---
**Author:** ![Daylate](https://avatars.discourse-cdn.com/v4/letter/d/9dc877/32.png) [@Daylate](https://boards.straightdope.com/u/Daylate)\ **Post date:** [March 2, 2011, 11:55pm UTC](https://boards.straightdope.com/t/can-you-actually-reverse-the-polarity/573235/27 "2011-03-02T23:55:22Z")
> [@](#): > > I hooked the battery charger up backwards on my rig a while back. Got lucky, the charger was really old and it died before it hurt the vehicle. > > And when I say died, be thinking of a Viking funeral pyre. And you didn’t get a video of it???! For shame!! ---
**Author:** ![LouisB](https://avatars.discourse-cdn.com/v4/letter/l/dfb087/32.png) [@LouisB](https://boards.straightdope.com/u/LouisB)\ **Post date:** [March 3, 2011, 12:04am UTC](https://boards.straightdope.com/t/can-you-actually-reverse-the-polarity/573235/28 "2011-03-03T00:04:02Z")
> [@The\_Hamster\_King](#): > > That’s why you should use an oscillation overthruster instead. I think I dated a girl who had one of those. She was quite fond of it. ---
**Author:** ![Fubaya](https://avatars.discourse-cdn.com/v4/letter/f/c2a13f/32.png) [@Fubaya](https://boards.straightdope.com/u/Fubaya)\ **Post date:** [March 3, 2011, 12:39am UTC](https://boards.straightdope.com/t/can-you-actually-reverse-the-polarity/573235/29 "2011-03-03T00:39:58Z")
If you plug a computer in backwards, the internet will consist mostly of women putting their clothes on. ---
**Author:** ![outlierrn](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/outlierrn/32/3005_2.png) [@outlierrn](https://boards.straightdope.com/u/outlierrn)\ **Post date:** [March 3, 2011, 2:58am UTC](https://boards.straightdope.com/t/can-you-actually-reverse-the-polarity/573235/30 "2011-03-03T02:58:44Z")
Is there actually any system on a galaxy class starship that _can’t_ have it’s polarity, how shall I put it, finessed? ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [March 3, 2011, 3:01am UTC](https://boards.straightdope.com/t/can-you-actually-reverse-the-polarity/573235/31 "2011-03-03T03:01:42Z")
I was always so afraid of putting in batteries facing the wrong way. Now you’re telling me for small loads it’s no biggie? Also, if you reverse the polarity of static you can fly. ---
**Author:** ![Sunspace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sunspace/32/1250_2.png) [@Sunspace](https://boards.straightdope.com/u/Sunspace)\ **Post date:** [March 3, 2011, 3:12am UTC](https://boards.straightdope.com/t/can-you-actually-reverse-the-polarity/573235/32 "2011-03-03T03:12:20Z")
> [@Fubaya](#): > > If you plug a computer in backwards, the internet will consist mostly of women putting their clothes on. And if the modem is circularly-polarized, they start knitting sweaters. ---
**Author:** ![thelabdude](https://avatars.discourse-cdn.com/v4/letter/t/dc4da7/32.png) [@thelabdude](https://boards.straightdope.com/u/thelabdude)\ **Post date:** [March 3, 2011, 3:13am UTC](https://boards.straightdope.com/t/can-you-actually-reverse-the-polarity/573235/33 "2011-03-03T03:13:53Z")
A flashlight, reverse polarity may woirk fine. A radio or ipod? who knows. ---
**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:** [March 3, 2011, 3:18am UTC](https://boards.straightdope.com/t/can-you-actually-reverse-the-polarity/573235/34 "2011-03-03T03:18:51Z")
> [@thelabdude](#): > > A flashlight, reverse polarity may woirk fine. A radio or ipod? who knows. Well, I expect the radio and ipod have diodes, as would a flashlight if it’s one of the newer ones with LEDs (i.e. diodes). Direction of current will matter. ---
**Author:** ![Gorsnak](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gorsnak/32/7587_2.png) [@Gorsnak](https://boards.straightdope.com/u/Gorsnak)\ **Post date:** [March 3, 2011, 4:04am UTC](https://boards.straightdope.com/t/can-you-actually-reverse-the-polarity/573235/35 "2011-03-03T04:04:38Z")
You can reverse the polarity on speakers and it doesn’t matter a bit. Unless you have multiple speakers playing the same signal and you reverse the polarity on some but not all of them. Do that and you’ll end up with lots of funky phase interference nulls. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [March 3, 2011, 4:11am UTC](https://boards.straightdope.com/t/can-you-actually-reverse-the-polarity/573235/36 "2011-03-03T04:11:38Z")
Quoth **Crafter\_Man** : > [@](#): > > Devices with power switches usually have polarized plugs, since you want to switch the hot and not the neutral. Thanks, I knew there was another scenario I was forgetting. Point is, doing it the other way around will still work, just not as safely. ---
**Author:** ![thelabdude](https://avatars.discourse-cdn.com/v4/letter/t/dc4da7/32.png) [@thelabdude](https://boards.straightdope.com/u/thelabdude)\ **Post date:** [March 3, 2011, 4:19am UTC](https://boards.straightdope.com/t/can-you-actually-reverse-the-polarity/573235/37 "2011-03-03T04:19:27Z")
> [@Bryan\_Ekers](#): > > Well, I expect the radio and ipod have diodes, as would a flashlight if it’s one of the newer ones with LEDs (i.e. diodes). Direction of current will matter. You are right, even the newer LED flashlights wouldn’t work. At least they wouldn’t be damaged. ---
**Author:** ![Snnipe\_70E](https://avatars.discourse-cdn.com/v4/letter/s/b5a626/32.png) [@Snnipe\_70E](https://boards.straightdope.com/u/Snnipe_70E)\ **Post date:** [March 3, 2011, 4:42am UTC](https://boards.straightdope.com/t/can-you-actually-reverse-the-polarity/573235/38 "2011-03-03T04:42:48Z")
> [@yabob](#): > > DC motors will just spin in the opposite direction. Whether that’s useful or not depends on the application. DC motors with perminate magnetic fields. DC motors with series or shunt fields will turn the same way. Traction elevator motors change direction by reversing the polarity on the externally excited field. They have 5 or 6 different field windings. ---
**Author:** ![Autolycus](https://avatars.discourse-cdn.com/v4/letter/a/22d042/32.png) [@Autolycus](https://boards.straightdope.com/u/Autolycus)\ **Post date:** [March 3, 2011, 5:17am UTC](https://boards.straightdope.com/t/can-you-actually-reverse-the-polarity/573235/39 "2011-03-03T05:17:19Z")
ALL the polarities are reversed on Opposite Day! ---
**Author:** ![Yllaria](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/yllaria/32/3452_2.png) [@Yllaria](https://boards.straightdope.com/u/Yllaria)\ **Post date:** [March 3, 2011, 5:46am UTC](https://boards.straightdope.com/t/can-you-actually-reverse-the-polarity/573235/40 "2011-03-03T05:46:30Z")
> [@Chronos](#): > > One of my favorite SDMB posts ever was someone saying that he plugged a lamp in backwards, and it started emitting antiphotons. . . That was Enola Straight - [here.](http://boards.straightdope.com/sdmb/showthread.php?t=130145&highlight=polarity) [Previous page](https://boards.straightdope.com/t/can-you-actually-reverse-the-polarity/573235.md?page=1) [Next page](https://boards.straightdope.com/t/can-you-actually-reverse-the-polarity/573235.md?page=3)