1. PF Insights is off to a great start! Fresh and interesting articles on all things science and math. Here: PF Insights

Why Things turn themselves on

  1. This happens a lot, some technology turns on randomly, or things open by themselves. Recently, my battery run wireless Sirius radio turned on randomly at night, and right after, the sink turned on by itself (It's a movement detection sink so it's electronic). Nothing could have got in the way of the sink for it to turn on. I know there's probably an easy explanation to it, but I was wondering what it was. Maybe circuits are closing by themselves somehow? If so how would that happen, anyways, I'd appreciate any info you have. You can probably I'm quite bad at physics, but after some internet searches, I decided to post here because I'm just curious as to why these things happen.
     
  2. jcsd
  3. SteamKing

    SteamKing 8,937
    Staff Emeritus
    Science Advisor
    Homework Helper

    You know, motion detection systems don't discriminate. They don't say, "There's John. He's waving his hand. I'll turn on the faucet now." If your MD sink is turning on at night, it means you are not alone in your apartment.

    But then again, these things aren't perfect, either. Maybe your gizmos just have a short or something in the circuitry.
     
  4. jedishrfu

    Staff: Mentor

    Reminds me of the quote "Ghosts in the Machine" by Ryle

    http://en.wikipedia.org/wiki/Ghost_in_the_machine

    Most likely a faulty switch for the radio that has partial contact.

    For the sink maybe its got a slow leak where the water drop triggers the movement sensor.

    For any plugged in devices, its most likely an electrical spike.
     
  5. Thanks, it definitely wasn't a person that turned it on, It was just in the other room and I was the only one there. Also thanks for the answers, I can definitely see a water drip turning it on. And the radio actually went on twice, so maybe it does have partial contact? But with that, what makes it still randomly turn on, if the switch is somehow off, why does it turn on sometimes and not other times?
     
  6. jedishrfu

    Staff: Mentor

    For a faulty switch it could be a gust of air blowing on or across the switch with just enough pressure to make contact or it could be some local vibration like a truck or car passing by or even by you closing a door noisily...
     
  7. jedishrfu

    Staff: Mentor

    Your question reminded me of a haunted house story I heard in college. The profs in our physics dept were called to investigate a haunted house. It was said that the walls made noises and that the piano played strangely and that snow melted around the house but no where else.

    What they found was the wall insulation wasn't nailed at the bottom it just hung loosely and that the piano had a broken music damper. The house was situated on a gravel pot that was connected underground to the nearby railroad tracks so when the train passed by the vibrations would be routed to the house causing the wall noises and the broken piano. The melted snow was due to the concrete apron absorbing microwave radiation from a nearby tv and radio station farm.
     
  8. PhysicoRaj

    PhysicoRaj 437
    Gold Member

    For the sink the explanation seems plausible. But for the radio, John is not alone!

    I have experienced this many times before. I always have my radio pugged in, but switched off at the socket switch. Then sometimes I hear the static, as if it is tuning by itself. I had first thought of a defective switch, but even after replacing the switch, it did not stop.

    My mobile sometimes switches off by itself. I checked the battery, it was full; signal strength-full. I haven't scheduled any auto-power-on/off operations.

    Strange is that these occur simultaneously. Even stranger is that these are accompanied by a strong humming noise from the transformer, at all other times it hummed gently. (my house is right next to a 11400v-240v transformer).
     
  9. A.T.

    A.T. 5,676
    Gold Member

  10. AlephZero

    AlephZero 7,300
    Science Advisor
    Homework Helper

    We once had a similar situation at work. There was a big open plan office with lots of computer workstations, which were used as a number-crunching network when they were not being used interactively by the engineers. The number crunching jobs were suspended if there was any interaction with the mouse or keyboard.

    We noticed something strange was happening every night. All the computers would go back into "interactive mode" several times each night, in a rapid wave pattern that went from one end of the office to the other. We couldn't find any glitches in the software, and the pattern of them waking up didn't make sense if there was an intruder in the building, or somebody trying to hack into the system.

    Eventually we found the cause. The company had hired some new security guards who were fitness enthusiasts. Instead of walking on their regular night patrols they were running, and the vibration through the floor was enough to shake the mice on most of the desks and wake up the computers.
     
  11. SteamKing

    SteamKing 8,937
    Staff Emeritus
    Science Advisor
    Homework Helper

    Who said anything about another person being in the apartment with the mysteriously operating faucet?
     
  12. PhysicoRaj

    PhysicoRaj 437
    Gold Member

    But my cell phone is no motion detector. It is not sensitive to anything except electromagnetic radiation. I can drop it on to the floor (from a small height) and it does not switch off. It switches off only when my radio hisses and when that transformer goes mad.
     
  13. NascentOxygen

    Staff: Mentor

    At scheduled times of the day and night electric power companies send audio tones over the mains to switch on & off various devices, in particular, off-peak hot water systems, so these only use electricity at the times of cheaper tarriffs. You can often hear these tones, like morse code signals using a buzzer. If these find their way into electronic devices, the device may be caused to exhibit unexpected behaviour.
     
  14. PhysicoRaj

    PhysicoRaj 437
    Gold Member

    So may be this was what I heard from the transformer. A radio picking up this is understandable. Surprising that it can induce currents in my phone!
     
Know someone interested in this topic? Share a link to this question via email, Google+, Twitter, or Facebook

Have something to add?

0
Draft saved Draft deleted