# Faraday Cages go to the Movies. **URL:** \ **Category:** Factual Questions\ **Created:** [June 28, 2004, 4:13am UTC](https://boards.straightdope.com/t/faraday-cages-go-to-the-movies/252499 "2004-06-28T04:13:30Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Pentax](https://avatars.discourse-cdn.com/v4/letter/p/dc4da7/32.png) [@Pentax](https://boards.straightdope.com/u/Pentax)\ **Post date:** [June 28, 2004, 4:13am UTC](https://boards.straightdope.com/t/faraday-cages-go-to-the-movies/252499/1 "2004-06-28T04:13:30Z")
Everytime I go to the movies, they tell me to turn off my cell phone. If they are so concerned with cell phones, why don’t they just put up metal mesh wall paper, and create a faraday cage, which according to my grade 12 physics will stop radio waves. How much could it cost to put up a faraday cage around a movie theater? Wouldn’t it be worth it to stop those idgets from spoiling the movie with their cell phones? ---
**Author:** ![Cisco](https://avatars.discourse-cdn.com/v4/letter/c/ccd318/32.png) [@Cisco](https://boards.straightdope.com/u/Cisco)\ **Post date:** [June 28, 2004, 4:56am UTC](https://boards.straightdope.com/t/faraday-cages-go-to-the-movies/252499/2 "2004-06-28T04:56:05Z")
> [@Pentax](#): > > How much could it cost to put up a faraday cage around a movie theater? Wouldn’t it be worth it to stop those idgets from spoiling the movie with their cell phones? Obviously too much. No one is stupid enough to blame the theatre when a guest’s cellphone rings therefore it’s not their problem therefore they aren’t going to spend money on it. I personally haven’t heard a phone ring in a theatre in years and I go to the movies quite often. Even when cell phones were first getting really popular in the late 90s and they did ring in theatres a lot it didn’t exactly spoil the movie. _Maybe_ new theatres will be built with something like this but I can’t see a single theatre owner justifying the cost of retrofitting his entire structure to stop the occasional ringtone. ---
**Author:** ![wireless](https://avatars.discourse-cdn.com/v4/letter/w/f14d63/32.png) [@wireless](https://boards.straightdope.com/u/wireless)\ **Post date:** [June 28, 2004, 5:24am UTC](https://boards.straightdope.com/t/faraday-cages-go-to-the-movies/252499/3 "2004-06-28T05:24:08Z")
1. It’s expensive. 2. It may not be legal - the wireless company has a license under federal law (FCC) to provide service in that area, and has generally paid handsomely for the opportunity, counting on being able to make money from customers. I’m not sure regular business establishments can just not allow the wireles companies to operate “within their borders”. Obviously there are exceptions for situations like hospitals, etc. (Maybe someone else can elucidate this further - I’ve always kind of wondered about the definitive answer to this myself). 3. It would stop all calls - even for phones on vibrate - which certain people may want/need during the movie/performance. If a person gets a call and it doesn’t bother anyone else, whats the problem? On re-read, this sounds like it could come across a bit snarky, which I’m not intending at all. Just listing some facts (I hope!) as I understand them. ---
**Author:** ![Lynn\_Bodoni](https://avatars.discourse-cdn.com/v4/letter/l/e47c2d/32.png) [@Lynn\_Bodoni](https://boards.straightdope.com/u/Lynn_Bodoni)\ **Post date:** [June 28, 2004, 5:24am UTC](https://boards.straightdope.com/t/faraday-cages-go-to-the-movies/252499/4 "2004-06-28T05:24:09Z")
As **Cisco** said, it would cost too much. I don’t know much about them, but I imagine that they would be a pain and expense to maintain, too. Movie theater technology might also come up with some gizmo which CAN NOT be activated in a Faraday cage. It’s not all that likely, but it’s possible. I’d also rather that parents have the option to have their cell phones on “vibrate”, so that sitters can reach them in an emergency. Other people also have emergencies, as well. As long as the phones are on “vibrate”, and the person receiving the call steps out of the theater itself to take the call, I don’t begrudge other people their electronic leashes. ---
**Author:** ![Ranchoth](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ranchoth/32/1066_2.png) [@Ranchoth](https://boards.straightdope.com/u/Ranchoth)\ **Post date:** [June 28, 2004, 5:39am UTC](https://boards.straightdope.com/t/faraday-cages-go-to-the-movies/252499/5 "2004-06-28T05:39:14Z")
This’d probably present a problem for people who really _need_ to have a cellphone or a pager handy. Like someone on an organ-transplant list, or someone who works on a bomb squad. One weird, freak occurance where blocking a pager or cellphone call causes a really _serious_ problem, and boom…lawsuit city. ---
**Author:** ![engineer\_comp\_geek](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/engineer_comp_geek/32/504_2.png) [@engineer\_comp\_geek](https://boards.straightdope.com/u/engineer_comp_geek)\ **Post date:** [June 28, 2004, 5:52am UTC](https://boards.straightdope.com/t/faraday-cages-go-to-the-movies/252499/6 "2004-06-28T05:52:23Z")
Usually if you try and retrofit something like this into a public place a bunch of people complain usually for the reason that Ranchoth states, it interferes with emergency communications. There’s no way you can retrofit it into an existing theatre without ticking someone off. However, if you build the building out of materials that naturally form a faraday cage (like that wire mesh stuff that they spray stuff over to make a wall) then nobody complains. Go figure. ---
**Author:** ![JerH](https://avatars.discourse-cdn.com/v4/letter/j/bb73d2/32.png) [@JerH](https://boards.straightdope.com/u/JerH)\ **Post date:** [June 28, 2004, 2:08pm UTC](https://boards.straightdope.com/t/faraday-cages-go-to-the-movies/252499/7 "2004-06-28T14:08:36Z")
> [@wireless](#): > > 1. It may not be legal - the wireless company has a license under federal law (FCC) to provide service in that area, and has generally paid handsomely for the opportunity, counting on being able to make money from customers. I’m not sure regular business establishments can just not allow the wireles companies to operate “within their borders”. Obviously there are exceptions for situations like hospitals, etc. (Maybe someone else can elucidate this further - I’ve always kind of wondered about the definitive answer to this myself). They have a license, but not a requirement to provide service in particular areas; if it was a requirement, my cell phone company would be in big trouble for the big holes in their coverage areas. That said - I don’t think it’s generally written into law that private businesses have to accomodate other private businesses, particularly when doing so might infringe on their own. ---
**Author:** ![Patty\_O\_Furniture](https://avatars.discourse-cdn.com/v4/letter/p/96bed5/32.png) [@Patty\_O\_Furniture](https://boards.straightdope.com/u/Patty_O_Furniture)\ **Post date:** [June 28, 2004, 3:10pm UTC](https://boards.straightdope.com/t/faraday-cages-go-to-the-movies/252499/8 "2004-06-28T15:10:30Z")
I thought they were already doing this. I never get signal any more when I go into a theater, even when I sit way up in the nosebleed section of the “stadium seating”. Right outside the theater door, I get full signal (5 bars). ---
**Author:** ![Jurph](https://avatars.discourse-cdn.com/v4/letter/j/50afbb/32.png) [@Jurph](https://boards.straightdope.com/u/Jurph)\ **Post date:** [June 28, 2004, 3:21pm UTC](https://boards.straightdope.com/t/faraday-cages-go-to-the-movies/252499/9 "2004-06-28T15:21:02Z")
While a Faraday Cage is a more elegant solution with no moving parts or power requirements, it looks like the quick fix is to use [jammers](http://slate.msn.com/id/2092059/). Apparently from the article’s text, > [@](#): > > According to the FCC, cell-phone jammers should remain illegal. Since commercial enterprises have purchased the rights to the spectrum, the argument goes, jamming their signals is a kind of property theft. But there are countries with less draconian rules. **France, for instance, seems to turn a blind eye to the active use of cell-phone jammers in movie theaters** , and countries such as China, Russia, and Israel either permit use of these technologies, or are very lax when it comes to enforcing restrictions. The article also discusses the passive jamming approach you highlighted. If a theater used active jammers, any of the personnel you mentioned above (organ transplant candidates, EMTs, etc.) could probably see the manager before the show and request that either (a) their phone be watched by the projectionist, or (b) the jammer in their theater be deactivated. I imagine in the big “ego” cities (LA, DC, NYC) that you’d have all sorts of characters demanding this special treatment, but that in most other markets, the silence would be a blissful boon. ---
**Author:** ![TellMeI\_mNotCrazy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tellmei_mnotcrazy/32/3419_2.png) [@TellMeI\_mNotCrazy](https://boards.straightdope.com/u/TellMeI_mNotCrazy)\ **Post date:** [June 28, 2004, 3:24pm UTC](https://boards.straightdope.com/t/faraday-cages-go-to-the-movies/252499/10 "2004-06-28T15:24:57Z")
> [@Attrayant](#): > > I thought they were already doing this. I never get signal any more when I go into a theater, even when I sit way up in the nosebleed section of the “stadium seating”. Right outside the theater door, I get full signal (5 bars). I figure they’re doing something similar at my local hospital - outside the emergency room doors, full signal. Two steps towards the door, (and all throughout the hospital) no signal whatsoever. ---
**Author:** ![Ethilrist](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ethilrist/32/4604_2.png) [@Ethilrist](https://boards.straightdope.com/u/Ethilrist)\ **Post date:** [June 28, 2004, 3:34pm UTC](https://boards.straightdope.com/t/faraday-cages-go-to-the-movies/252499/11 "2004-06-28T15:34:07Z")
> [@Cisco](#): > > I personally haven’t heard a phone ring in a theatre in years. Me,neither. I would actually like to credit cell phones with convincing people with pagers to set the things to vibrate; I rarely hear pagers go off anymore, either. Now, people _talking_ on cell phones in theatres, that’s a different story… ---
**Author:** ![Bosda\_Di\_Chi\_of\_Tricor](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bosda_di_chi_of_tricor/32/16845_2.png) [@Bosda\_Di\_Chi\_of\_Tricor](https://boards.straightdope.com/u/Bosda_Di_Chi_of_Tricor)\ **Post date:** [June 28, 2004, 4:13pm UTC](https://boards.straightdope.com/t/faraday-cages-go-to-the-movies/252499/12 "2004-06-28T16:13:10Z")
Was I the only Doper to hope that this thread was all about the electrical equipment used in the old Univeral Frankenstein films? ☹ ---
**Author:** ![engineer\_comp\_geek](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/engineer_comp_geek/32/504_2.png) [@engineer\_comp\_geek](https://boards.straightdope.com/u/engineer_comp_geek)\ **Post date:** [June 28, 2004, 5:33pm UTC](https://boards.straightdope.com/t/faraday-cages-go-to-the-movies/252499/13 "2004-06-28T17:33:34Z")
All of the laboratories in old movies contain: 1. A Jacob’s Ladder (really cool, but serves no useful purpose) 2. An oscilloscope displaying some sort of fancy moving pattern (the pattern also serves no useful purpose until you get it standing still, at which point it also ceases to be interesting to the typical movie watcher) 3. Hi opal! 4. A large assortment of knife switches, knobs, and dials, none of which appear to actually be wired to anything A faraday cage is just a fancy name for a metal box. Keep on the lookout for threads mentioning Jacob’s Ladders if you want the really cool sci-fi stuff. Jacob’s Ladder link: [http://www.kronjaeger.com/hv/hv/exp/jacob/](http://www.kronjaeger.com/hv/hv/exp/jacob/) And, just to keep this post on topic, here’s some info about faraday cages as well: [http://www.boltlightningprotection.com/Elemental\_Faraday\_Cage.htm](http://www.boltlightningprotection.com/Elemental_Faraday_Cage.htm) ---
**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:** [June 28, 2004, 6:08pm UTC](https://boards.straightdope.com/t/faraday-cages-go-to-the-movies/252499/14 "2004-06-28T18:08:39Z")
> [@engineer\_comp\_geek](#): > > 1. An oscilloscope displaying some sort of fancy moving pattern (the pattern also serves no useful purpose until you get it standing still, at which point it also ceases to be interesting to the typical movie watcher) These are almost always _lissajous_ patterns, which are formed by feeding different waveforms to the horizontal and vertical axes. We used static ones (formed by two signals of the same frequency, in or out of phase) to test turns ratio in certain types of toroidal transformers where I used to work. When the two signals are in phase, it forms a diagonal line. ---
**Author:** ![BobLibDem](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/boblibdem/32/3149_2.png) [@BobLibDem](https://boards.straightdope.com/u/BobLibDem)\ **Post date:** [June 28, 2004, 6:37pm UTC](https://boards.straightdope.com/t/faraday-cages-go-to-the-movies/252499/15 "2004-06-28T18:37:29Z")
I don’t know why it would be illegal to construct any building that would block phone transmissions. My office building has no Faraday cage, but its construction is such that cell phones may only be used near a window. Building constructors have no obligation to make their structures transparent to cell phones, do they? ---
**Author:** ![kellner](https://avatars.discourse-cdn.com/v4/letter/k/c2a13f/32.png) [@kellner](https://boards.straightdope.com/u/kellner)\ **Post date:** [June 28, 2004, 6:55pm UTC](https://boards.straightdope.com/t/faraday-cages-go-to-the-movies/252499/16 "2004-06-28T18:55:13Z")
In a town were I lived there was a cinema (built in the late nineties) that was advertised as cell phone proof - and it was. However the outer shell of the building was mostly metal anyway, so it might have been unintentional. ---
**Author:** ![ozonelover](https://avatars.discourse-cdn.com/v4/letter/o/3bc359/32.png) [@ozonelover](https://boards.straightdope.com/u/ozonelover)\ **Post date:** [June 28, 2004, 10:02pm UTC](https://boards.straightdope.com/t/faraday-cages-go-to-the-movies/252499/17 "2004-06-28T22:02:57Z")
A laboratory is certainly the place for a “Jacob’s Ladder”; they produce poisonous nitrogen oxides, and a variant process was used at one time to manufacture nitric acid. Thank you. ---
**Author:** ![Trigonal\_Planar](https://avatars.discourse-cdn.com/v4/letter/t/0ea827/32.png) [@Trigonal\_Planar](https://boards.straightdope.com/u/Trigonal_Planar)\ **Post date:** [June 29, 2004, 1:09am UTC](https://boards.straightdope.com/t/faraday-cages-go-to-the-movies/252499/18 "2004-06-29T01:09:12Z")
Laboratories may be the \*ideal \* place for a Jacob’s ladder, but I can assure you they’ll live in a basement just fine 🙂 ---
**Author:** ![Tim\_T-Bonham.net](https://avatars.discourse-cdn.com/v4/letter/t/46a35a/32.png) [@Tim\_T-Bonham.net](https://boards.straightdope.com/u/Tim_T-Bonham.net)\ **Post date:** [June 29, 2004, 1:41am UTC](https://boards.straightdope.com/t/faraday-cages-go-to-the-movies/252499/19 "2004-06-29T01:41:52Z")
Recently, a school in Europe installed a jammer, for the purpose of preventing students from cheating on exams. Students were text messaging questions to friends, who would look up the answers and send them back. Apparently enough of a problem that the school went to the effort of obtaining a government variance to allow them to operate this jammer. ---
**Author:** ![3.885AM](https://avatars.discourse-cdn.com/v4/letter/3/58956e/32.png) [@3.885AM](https://boards.straightdope.com/u/3.885AM)\ **Post date:** [June 29, 2004, 2:41am UTC](https://boards.straightdope.com/t/faraday-cages-go-to-the-movies/252499/20 "2004-06-29T02:41:08Z")
Any shielding that would block cell phone signals would also block police and fire radio signals, might be some public safety issues here. [Next page](https://boards.straightdope.com/t/faraday-cages-go-to-the-movies/252499.md?page=2)