# Is wireless power possible? **URL:** \ **Category:** Factual Questions\ **Created:** [April 24, 2002, 5:32pm UTC](https://boards.straightdope.com/t/is-wireless-power-possible/105396 "2002-04-24T17:32:40Z")\ **Posts on this page:** 10\ **Page:** 2
**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\ **Post date:** [April 25, 2002, 11:14am UTC](https://boards.straightdope.com/t/is-wireless-power-possible/105396/21 "2002-04-25T11:14:38Z")
> [@](#): > > yes its called a transformer (though only over short distances). The same principle was tried (used?) in pacemakers. It’s used in a lot of household appliances as well. My Braun electric toothbrush has no electrical contacts for charging the battery; instead it uses induction to “beam” power through the plastic case. Same for my rechargeable vacuum cleaner. A neat application I just read about is an endoscopic camera capsule. A little capsule contains a camera, transmitter, and a receiver for beamed power. You swallow it and point a radio transmitter at it, and it returns images from your stomach or intestine. (It’s not reusable, thank god.) Apparently batteries don’t last long enough, and are more dangerous if they leak. ---
**Author:** ![Musicat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/musicat/32/20189_2.png) [@Musicat](https://boards.straightdope.com/u/Musicat)\ **Post date:** [April 25, 2002, 1:33pm UTC](https://boards.straightdope.com/t/is-wireless-power-possible/105396/22 "2002-04-25T13:33:56Z")
**scr4,** you’re probably thinking about the [“Pill Camera”](http://abcnews.go.com/sections/living/DailyNews/pillcamera020419.html), which is powered by 2 batteries. It transmits to a video receiver/recorder worn on the body for up to 8 hours. And **engineer\_comp\_geek,** I always thought the reason the toll lane sensors didn’t use RFID (non-battery) principles is because they were designed years ago, before RFID was refined to the simple products of today, like the Mobil Speedpass[sup]TM[/sup]. You mentioned the time it takes to respond if a capacitor has to be charged up first. But aren’t we talking about milliseconds here? From your experience, would a 5-mph (the speed limit) car moving thru a tollbooth, considering distance from sensor, etc., be too fast or too far for modern RFID? ---
**Author:** ![N9IWP](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/n9iwp/32/3154_2.png) [@N9IWP](https://boards.straightdope.com/u/N9IWP)\ **Post date:** [April 25, 2002, 2:54pm UTC](https://boards.straightdope.com/t/is-wireless-power-possible/105396/23 "2002-04-25T14:54:18Z")
getting power from solar sattelites. You put up big solar arrays, then beam the power down with microwaves. Jerry Pournelle is a big advocate of this. yes, birds who stay too long in the beam get cooked, but birds get killed hitting windmills too. I’m not complete sold, but it is worth considering IMHO Brian ---
**Author:** ![AndrewL](https://avatars.discourse-cdn.com/v4/letter/a/3d9bf3/32.png) [@AndrewL](https://boards.straightdope.com/u/AndrewL)\ **Post date:** [April 25, 2002, 3:19pm UTC](https://boards.straightdope.com/t/is-wireless-power-possible/105396/24 "2002-04-25T15:19:12Z")
Solar power sattelites won’t be built anytime soon for a number of reasons. First of all, they make no economic sense whatsoever right now. It costs so much to put things in orbit that you’re better off just building more solar panels and keeping them on the ground. The extra sunlight you get by putting the arran in orbit doesn’t offset the cost of putting it there. Until we have much cheaper launch costs or the ability to make solar panels in orbit from asteroid or moon-mined materials, it would just be silly. Secondly, a giant solar-powered microwave beam in space isn’t just a power gathering device; it would be easily useable as an Orbital Death Ray. What happenes when you point a high-powered solar power sattelite at, say, London, and leave it pointing there at high power for a while? Can’t be good for the residents. ---
**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\ **Post date:** [April 25, 2002, 3:51pm UTC](https://boards.straightdope.com/t/is-wireless-power-possible/105396/25 "2002-04-25T15:51:21Z")
> [@](#): > > \*Originally posted by Musicat \* > \*\ ***scr4,** you’re probably thinking about the [“Pill Camera”](http://abcnews.go.com/sections/living/DailyNews/pillcamera020419.html), which is powered by 2 batteries. \*\* No, I read about a product or prototype that addresses the limitation of the Pill Camera - namely the limited battery capacity. The current battery-powered ones can’t take very many pictures before the battery gives out. With beamed power there is no limit to how long it can work, allowing it to keep taking pictures all the way down through the intestine. I’m sorry I can’t find a cite right now. ---
**Author:** ![SmackFu](https://avatars.discourse-cdn.com/v4/letter/s/53a042/32.png) [@SmackFu](https://boards.straightdope.com/u/SmackFu)\ **Post date:** [April 25, 2002, 4:55pm UTC](https://boards.straightdope.com/t/is-wireless-power-possible/105396/26 "2002-04-25T16:55:09Z")
My underlying thought in the OP was to have your house or other small indoor area be “electrified”. With the move in computers toward wireless everything for connections (Bluetooth, HomeRF, 802.11b), it seems like the only remaining limitation is the power plug, and short-range wireless power would be the obvious solution. Shouda phrased the OP better. Too bad, it seems like the only thing that might work for this purpose is Tesla’s scheme, which has it’s own problems. ---
**Author:** ![DocCathode](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/doccathode/32/18773_2.png) [@DocCathode](https://boards.straightdope.com/u/DocCathode)\ **Post date:** [April 25, 2002, 5:14pm UTC](https://boards.straightdope.com/t/is-wireless-power-possible/105396/27 "2002-04-25T17:14:38Z")
> [@](#): > > \*Originally posted by engineer\_comp\_geek \* > \*\* > > I’ve designed RF-ID (Radio Frequency Identification) components into systems. > . \*\* I’d like to formally request an ask the Engineering Geek Guy thread. I’m working on many pointless and often bizzare projects and I have many questions. All the books I’ve seen on electricity and electronics are very elementary (Ohm’s law VR=I let’s spend 50 pages explaining that in small words) or very advanced (So we find that a reciprocating-mosfet-heterodyne-potzrebie has the same grommishing coefficient as…) ``` Now if I could only find a Doper who's a mechanical engineer, I could build that tensegrity dining room set. ``` ---
**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:** [April 25, 2002, 8:34pm UTC](https://boards.straightdope.com/t/is-wireless-power-possible/105396/28 "2002-04-25T20:34:46Z")
> [@](#): > > (Ohm’s law VR=I let’s spend 50 pages explaining that in small words) Or let’s just spend one line to point out that it’s V = IR. ---
**Author:** ![bbeaty](https://avatars.discourse-cdn.com/v4/letter/b/c0e974/32.png) [@bbeaty](https://boards.straightdope.com/u/bbeaty)\ **Post date:** [April 26, 2002, 8:01am UTC](https://boards.straightdope.com/t/is-wireless-power-possible/105396/29 "2002-04-26T08:01:15Z")
> [@](#): > > \*Originally posted by DocCathode \* > > I’d like to formally request an ask the Engineering Geek Guy thread. Ah, that’s called SCI.ELECTRONICS.BASICS, see [http://groups.google.com/groups?group=sci.electronics.basics](http://groups.google.com/groups?group=sci.electronics.basics) Here’s my collection of links to various similar groups: [http://amasci.com/amateur/elehob.html#nws](http://amasci.com/amateur/elehob.html#nws) ---
**Author:** ![DocCathode](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/doccathode/32/18773_2.png) [@DocCathode](https://boards.straightdope.com/u/DocCathode)\ **Post date:** [April 26, 2002, 1:38pm UTC](https://boards.straightdope.com/t/is-wireless-power-possible/105396/30 "2002-04-26T13:38:10Z")
Re-Ohm’s Law It was a typo! I swear! I stand on my record of typos, missing characters and extra letters. Thanx to bbeaty. No, wait a minute! I’ll now be spending twice as much time on the web. That was your plan all along, wasn’t it? [Previous page](https://boards.straightdope.com/t/is-wireless-power-possible/105396.md?page=1)