Screen brightness affected by... electricity?

Discussion in 'MacBook' started by kagoatweed, Mar 22, 2009.

  1. kagoatweed macrumors newbie

    Nov 20, 2008
    This isn't really a problem, just an observation that I wanted some opinions on.

    I have the aluminum MacBook (<3) and it is often found on my desk, in front of my aluminum desk lamp. I was writing a paper and had one hand on my touchpad and touched my (off, but plugged in) light with my other hand. My screen dimmed just a little bit, approx the brightness between the two highest lighting levels.
    Even when not touching my touchpad, just touching my light, my screen did the same thing. Depending on WHERE on the lamp I touch, it affects the brightness... but only on the bell surrounding the light bulb, no other components of the light.

    Any ideas what causes this? :p
  2. jonbravo77 macrumors 6502a


    Feb 20, 2008
    Phoenix, AZ
    The lamp may not be completely grounded properly. When you touch it it closes the circuit. If your MB is plugged into the same outlet could be affecting the power. I wouldn't worry to much about it, if you are concerned try plugging the lamp into another plug, but you may end up getting the same result if that other plug is daisy chained off of the original outlet. Standard practice in homes. Just my thoughts...
  3. mousouchop macrumors 6502a


    Oct 22, 2008
    New York
    Yeah, the ambient light sensor in the Macbook sees the change of light when you touch the lamp in various spots altering the path of light when it bounces off your arm and hand and makes the screen adjust accordingly. Not rocket science. haha. That ambient sensor can pick up some very subtle lighting changes.

    It has nothing to do with electricity. Well, in a way it does because both things are running on electricity. Haha. But, the actual phenomenon happenings is just the sensor doing it's job. If you don't like it, then disable the brightness autoadjust feature in your system prefs.

    Hope this helps.
  4. NewMacbookPlz macrumors 68040


    Sep 28, 2008
    The light sensor is pretty sensitive.

    I had to shut mine off, just because at night, when using my MB on the couch while watching TV, it'd fluctuate the screen brightness based off how bright the TV image bouncing off the wall behind me was.

    It got really annoying, really fast =\
  5. morrisman1 macrumors 6502

    the most annoying thing about the light sensor i found was when you have a light behind you and moving your head puts the sensor in and out of your shadow, it would always adjust. i just turned it off, theres nothing wrong with doing it manually
  6. kagoatweed thread starter macrumors newbie

    Nov 20, 2008
    :O very cool! didn't even know i had one of those. it all makes sense now! :cool:

  7. STSNorthstar macrumors regular

    Sep 17, 2008
    This reminds me of my Dell Latitude. IT had a magnesium alloy lower case, and the paint wore off around a corner on it. if one arm was touching that corner, and i touched my desk lamp, i could feel my arm tingle on the dell. i even used my tongue to verify the elevrical connection.

    Don't judge me...
  8. tubbymac macrumors 65816


    Nov 6, 2008
  9. NewMacbookPlz macrumors 68040


    Sep 28, 2008
    Here, can you check this 9V battery for me? :D

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