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Measuring Microwave Output From A Laptop? 108

Posted by Cliff
from the will-our-laps-start-glowing-anytime-soon dept.
bethorphil asks: "I was shopping online for a laptop today, and as I was choosing my processor speed, I noticed that the clock frequency of a decent CPU (2.4 GHz) was about the same frequency as the radiation used in a microwave oven. This got me thinking about recent headlines of laptop heat causing male infertility. If the heat alone is a threat, It would make sense that holding a 40-watt microwave emitter in your lap could cause even more serious problems down the road. I assume (optimistically, perhaps) that laptops are designed to shield the user from radiation, and not just to protect the system from interference. , but what I'd really like is a way to test for myself how much microwave radiation actually comes from my laptop. So far, the most interesting thing my searches have come up with is this quack-tastic low emission PC, but actual tools for an amateur to measure this stuff seem hard to come by. What's the best way to find out if my laptop is nuking the family jewels?"
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Measuring Microwave Output From A Laptop?

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  • 40 watt microwave? (Score:5, Interesting)

    by dougmc (70836) <dougmc+slashdot@frenzied.us> on Saturday July 02, 2005 @07:00PM (#12970864) Homepage
    If the heat alone is a threat, It would make sense that holding a 40-watt microwave emitter in your lap could cause even more serious problems down the road.
    Yes, you have a 40 watt heater in your lap. But you do NOT have a 40 watt microwave emitter in your lap.

    As for how to measure the amount of microwave radiation a laptop emits, that would require special equipment that you are not likely to have at home. But the FCC does put serious limits on the RF that it's allowed to emit. I'll bet the actual microwave RF emitted is under a watt. Probably less than 1/10th of a watt.

    Now, if you have WiFi, that will emit about 250 mW of power when it's actively transmitting. Which is a small percentage of the time. But your WiFi card probably does emit more microwave radiation than the rest of the laptop combined ...

    As for microwaves causing infertility, that has yet to be really shown.

    • by dougmc (70836) <dougmc+slashdot@frenzied.us> on Saturday July 02, 2005 @07:06PM (#12970894) Homepage
      As for your `Laptops May Threaten Male Fertility' article, if you read it carefully, you'll find that NOWHERE does it say anything about microwaves.

      The story is about laptop heat, not microwaves. And sperm are best produced at about 94 degrees F (if memory serves me correctly), which is why the testicles are outside of the body -- so they can be cooler than body temperature.

      Anything that raises the temperature of the testicles above that will reduce sperm production -- be it a laptop, living in Texas, wearing tight underwear or a having a cat in your lap. This is well known.

      But as far as I know, the effect is temporary. Remove the laptop, move to Alaska, wear boxers, kick the cat off, and sperm production goes back up. But maybe somebody knows something I don't.

      Assuming I'm right, just keep the laptop (and cat) out of your lap while you're trying to knock your wife up, and you'll be fine.

      • What better slasdot topic can there be? "Imagine a beowulf cluster of DNA emitters which don't overheat..."
      • What an idiotic system. You would have thought by now they would have built better humans to where males produce sperm INSIDE the body at the normal temperature.

        Sheesh, we can put a man on the moon...
        • Hmmm... You are describing the female reproductive system where eggs (not sperm) is produce inside the body at normal temperature. Besides, men need their equipment on the outside to prove their manhood. Otherwise, they would be nothing but sissies. :P
        • sgant(178166) wrote: "What an idiotic system. You would have thought by now they would have built better humans to where males produce sperm INSIDE the body at the normal temperature."

          See, you've just pointed out one of the fallacies of "intelligent design". Any genuinely "intelligent designer" would have done a better job. Period. But I'm sure that the stupids who buy into this bullshit won't hear of it.

      • Assuming I'm right, just keep the laptop (and cat) out of your lap while you're trying to knock your wife up, and you'll be fine.

        Good advice. Most women probably would not appreciate attempts to use a laptop while impregnating them, and those cats have sharp claws.
      • Assuming I'm right, just keep the laptop (and cat) out of your lap while you're trying to knock your wife up, and you'll be fine.

        Given this was posted on Slashdot, don't you think the OP has more to worry about than his sperm? I mean, having a laptop on your lap is a sure-fire way to not get laid in the first place.

        I mean, being someone who posts on slashdot is a surefire way to not get laid in the first place.

        So, OP, stop worrying about your sperm and start worrying about how many FPS you can g

      • That's true, however the converse of this effect is that since warming ones balls is a form of contraception, and that laptop computers are capable of performing this function, it logically follows that, in the situation where you don't want to knock your wife up that you can use this as a justification for spending more time on said laptop. Granted, it's your wife's laptop that should be getting most of the attention but, this is Slashdot.
        • I knew of a guy at Michigan State in the sixties who spent some time before each date sitting naked on a wicker chair with the seat cut out, his scrotum dangling in hot water.
          • I read (many years ago) about an African tribe whose men regularly soaked their balls in hot water. They couldn't explain where the tradition came from (and had no idea how it worked) but it was done for the express purpose of contraception.
      • There's one other major cause of fertility problems, oestrogen like molecules.

        There are two key sources for absorbed oestrogen like molecules, pollution [bbc.co.uk] and soya.

        A just to make sure you get all the bang for you buck, they also causes birth defects [bbc.co.uk].

    • But you do NOT have a 40 watt microwave emitter in your lap.

      More's the pity, I'd love to get "Worked All States" while wardriving.
    • Of course, this depends on your particular laptop conforming to the standard. If its way out of tolerance, you can never tell. Check out a search on Medline and you'll see lots of experiments on rats with low-level microwaves, often modulated by a low frequency. It may be too late for you. Your jewels may already be cooked. As suggested above, quickly find a girfiriend and check it out. Be sure to let us know the results. Lets just hope you don't get quadruplets on the first shot.
    • >But the FCC does put serious limits on the RF
      >that it's allowed to emit. I'll bet the actual
      >microwave RF emitted is under a watt.
      >Probably less than 1/10th of a watt.

      Hmmmm... Perhaps you might want to look at CISPR22 or CFR 47 Part 15 (FCC limits on conducted and emitted radiation from (currently) 150kHz to only 1 GHz. Even if below Class A limits, you will be radiating more than 10mW.

      >Now, if you have WiFi, that will emit about
      >250 mW of power when it's actively
      >transmitting. Which
    • WiFi transmit power for almost all cards is 25 mW. 100 mW is the max legal limit without using automatic power control measures (reducing power when it's not needed) The max legal limit for WiFi is higher (There are even 1W amps), but 25 mW is the max from almost any laptop, and anything more than 100 mW without an external PA is unheard of. (I know of one card in existence that had transmit power over 100 mW)

      And as to stray emissions from the laptop itself - WAY less than the 1/10 W (100 mW) you mentio
      • First generation WRT54G from Linksys appears to use a broadcom based pccard for wifi. This card is definitely capable of transmitting at more then 100mw (tho not with the stock firmware)

        For that matter, the sitecom (RaLink) based card in my laptop cann be configured to transmit at 100mw with the stock drivers for Windows, and can be configured tot do a bit more when using some of the alternative drivers (on Linux and FreeBSD)

        So.. I would say there are cards around that go in laptops that can transmit at o
  • by secolactico (519805) on Saturday July 02, 2005 @07:02PM (#12970874) Journal
    What's the best way to find out if my laptop is nuking the family jewels?

    Breed. If your kids come out with extra limbs, scales-for-skin or superpowers, then it is.
  • by HotNeedleOfInquiry (598897) on Saturday July 02, 2005 @07:03PM (#12970881)
    Most modern high clock frequency CPU's have an internal phase-locked oscillator (in this case 2.4ghz) that's synced to a low-frequency external crystal. The Front Side Bus frequency is about the highest you could detect external to the CPU.
  • by Monte (48723) on Saturday July 02, 2005 @07:14PM (#12970935)
    I have a small sticker that when applied to your laptop will block all harmful RF energies!!. But wait! There's more! Apply one to your gas tank and you'll see a 30 horsepower increase!! as well as getting an extra 15 miles per gallon!!

    How much would you pay for this small miracle? Three hundred? Two hundred? NO! Today only I am ready to sell you this modern wonder of technology for a mere six payments of $19.99!!!

    Act now! Operators are standing by!
  • duh (Score:1, Insightful)

    by Anonymous Coward
    A 40 watt laptop != 40 watt microwave transmitter. Just because it's at a similar frequency doesn't mean it's a full-bore oven. Police radar|some motion detectors|etc uses microwave frequencies but you don't see birds flying through the beam being toasted.

    tard

  • The clock is 2.4Ghz (Score:3, Informative)

    by ArchieBunker (132337) on Saturday July 02, 2005 @07:20PM (#12970955) Homepage
    and might emit a few microwatts at best. The plastic case should stop that. Microwave ovens on the other hand are just a modern RF oven. You dump 800 watts into a cubic foot steel box, something is going to absorb that energy and convert it to heat.
  • Microwave test (Score:4, Interesting)

    by eagle486 (553102) on Saturday July 02, 2005 @07:21PM (#12970957)
    In same safety stores you can buy a plastic card that when held to a microwave will show you the amount of leakage. Just test your laptop with this. But I don't think you will see any microwaves coming from your laptop unless you have wifi card.
    • What's a safety store? I don't think I've ever seen one of those. The closest thing I can think of is a hardware store, but those are generally unsafety stores.
  • I doubt a laptop CPU emits enough microwave radiation to irradiate your gonads. It may run at 2.4 GHz but as I understand it, it emits plain non-microwave heat - the type you get when a resistor is heated by an electric current.

    It's well known that heat (hot bath, sauna, etc) causes a drop in male fertility, but it's temporary IIRC. Just don't use a laptop while trying to conceive a child.

    Of more concern are studies on microwave cooking that suggest it induces molecular changes to the food that may be har
    • I got this far in the article you linked to:

      Hertel not only conceived of the study and carried it out, he was one of eight participants. "To control as many variables as possible, we selected eight individuals who were strict macrobiotic diet participants from the Macrobiotic Institute at Kientel, Switzerland," Hertel explained. "We were all housed in the same hotel environment for eight weeks. There was no smoking, no alcohol and no sex." One can readily see that this protocol makes sense. ...and sorta l
    • by node 3 (115640) on Saturday July 02, 2005 @09:03PM (#12971371)
      However, it's a known fact that the mechanics of microwave cooking are fundamentally different from traditional cooking

      No, it's not. Like all forms of traditional heat-utilizing cooking, you heat up the food at some place, which heats the rest of it.

      Frying, baking, boiling, steaming, etc, all work like this. Microwaving, instead of heating the surface of the food, heats all of the water molecules within the food. This is exactly the same as if you had a knob and could change the temperature of the water without changing the rest of the food in any way. Any notion of "nutritional" changes are highly suspect. There's just no reason to believe microwaves, for example, could significantly change the vitamin or mineral content of the food.

      Microwaves are non-ionizing radiation. That means, roughly, that they don't knock atoms into pieces, and thus don't break atomic bonds. They just heat up matter, especially water, since water absorbs microwaves so well.

      Some label this pseudoscience.

      That's because it is. There's no valid scientific observation, and no logical scientific model, to suggest that microwave radiation directly affects the nutrition in food.

      Just because microwave ovens seem more magical than a frying pan does not excuse them from the rigors of science or the laws of reality.
      • by Anonymous Coward
        Actually, microwaves /do/ have more of an effect on the nutritional contents of food, especially vegetables. Traditionally, you cook vegetables in water. Microwaves get the temperature of the vegetables well above what it would be even boiling, and the higher the heat (and the addition of water by itself) means that microwaving vegetables loses more than 95% of the nutrients. Boiling loses about 90% for comparison. Letting it sit in cold or room temperature water loses 80% by itself, before any cooking
        • by node 3 (115640) on Saturday July 02, 2005 @11:25PM (#12971931)
          Actually, microwaves /do/ have more of an effect on the nutritional contents of food, especially vegetables.

          No, they don't. Microwave radiation does not affect food nutrition.

          I wasn't addressing whether boiling or microwaving vegetables are equally healthy. I was addressing microwave radiation.

          Re-read the poster I was replying to:

          Of more concern ... microwave cooking ... induces molecular changes to the food that may be harmful to humans ... the mechanics of microwave cooking are fundamentally different from traditional cooking

          So you bring up numbers (bogus sounding numbers at that*) that say boiling a vegetable is a little worse than setting it in water, and that microwaving it is slightly worse than that. Big deal. It's not magical molecule transforming rays doing it, it's just heat. Same with frying, baking, flame broiling, deep frying, stewing, etc.

          In other words, microwaving food is in the same realm as "traditional cooking", contrary to the pseudoscience the poster promoted.

          You are bringing up an entirely different point, which is whether microwaving vegetables or boiling vegetables is healthier. Something to ponder, if you really care about a 5% nutrient difference, but entirely separate from the question at hand.

          * 80% nutrient loss by setting a vegetable in cold water? Maybe if you mash it up, and set a small portion in a big bucket of water for a few days or something. Or maybe if you place a sliced apple in water for a half hour. How much does deep frying lose? I bet it's more than the supposed 15% in the microwave.

          Beyond that, the numbers are too round. Is it 92% for boiling, and 93% for microwave? Or did it actually come out 80%, 90% and 95%? Are you under-boiling, but over-microwaving? What vegetable is it? Etc.
          • It's not magical molecule transforming rays doing it, it's just heat.

            Well, I'm not a microwave engineer, but iirc the microwave oven creates standing waves of microwaves within the "cooking cavity" (for want of a better term). These standing waves induce water molecules in the substance being heated to oscillate, thus heating it.

            So yes, it is just heat, but the method of transferring the energy to the thing being heated is unique amongst cooking methods.

            Incidentally, it's this that is repsonsible for u
          • My question is this... are his veggies traceable to the NIST standard?
      • Microwaving, instead of heating the surface of the food, heats all of the water molecules within the food. This is exactly the same as if you had a knob and could change the temperature of the water without changing the rest of the food in any way.

        This isn't completely true. Microwaves can heat fat and sugars quite effectively, as well.

        That means, roughly, that they don't knock atoms into pieces, and thus don't break atomic bonds. They just heat up matter, especially water, since water absorbs micr

        • True, however, the rapid, high heat that microwaving can cause can cause chemical reactions in the food (conventional cooking does, as well).

          Exactly.

          The question at hand is whether microwaves do something unnatural to food, as compared to "traditional cooking".

          They don't. Yes, microwaving food is unique in the "signature" it leaves, but so it steaming, boiling, broiling, frying, baking, etc. It's fully in that same realm. It's *not* in the magical and scary realm that the original poster placed it.

          The
          • I know. I was being a little nit-picky since you said that microwave cooking doesn't "break atomic bonds". There's always some luddites/technophobes out there that think every new technology is killing them. Unfortunately some of them are students of Science, and can wrap their paranoia in plausible language. It then gets repeated until these myths turn into well known "facts" in public opinion.

            On the other hand, there is evidence that more mundane cooking methods are more dangerous. Barbecuing meats [newhousenews.com]

      • > > However, it's a known fact that the mechanics of microwave cooking
        > > are fundamentally different from traditional cooking

        > No, it's not. Like all forms of traditional heat-utilizing cooking,
        > you heat up the food at some place, which heats the rest of it.

        You are wrong.

        When I cook something in normal fashion, I can be sure that the temperature of the food is BELOW the temperature of my heat source - the grill, open fire, oven, steam, etc. Not so with microwave cooking - I can't reli
        • When I cook something in normal fashion, I can be sure that the temperature of the food is BELOW the temperature of my heat source

          The temperature of your flame is much, much higher than you will ever attain in a microwave.

          Certain parts of the food can reach temperatures never attained in normal cooking

          Consider this: Why can't you brown foods in a microwave without special equipment? The answer is that the temperature is limited by the boiling point of water (as with steaming/boiling/poaching/etc.)

          • Are you wilfully keeping yourself from understanding? Let me repeat - certain points in microwaved food may reach temperatures never reached outside (i.e. hotspots) - you have no simple way of telling. Contrast this to conventional cooking, where there is a straightfoward upper bound on temperature that _no_ part of the food will ever cross.

            > The temperature of your flame is much, much higher than you will ever attain in a microwave.

            No, wrong

            Take a look here: a domestic microwave oven can be used to [c2i.net]
    • by Anonymous Coward
      http://www.cspinet.org/nah/04_05/microwavemyths.pd f [cspinet.org]

      This was in the "Nutrition Action Health Letter" from the Center for Science in the Public Interest a few months ago. Its a very reputable publication (I recommend a subscription for anyone that tries to eat healthy).
    • Did you read the articles you're using as evidence?

      After all, how could you tell about subtle changes in a human's blood from eating microwaved food if smoking, booze, junk food, pollution, pesticides, hormones, antibiotics and everything else in the common environment were also present?

      In other words: the study was very theoretical, and environmental factors affect humans much more than anything a microwave can do to the food.

      That's why there was a gag order against slander. The study wasn't meaningfu
      • > Did you read the articles you're using as evidence?

        I read up on the older Swiss work several years ago. A gag order for it is just stupid.
        This is just a recent link I found with Google that references it.
        I didn't read the second paper, just it's abstract, which you quoted:

        > "High-pressure boiling, low-pressure boiling (conventional),
        > steaming and microwaving were the four domestic cooking processes used in this work . . . .
        > [W]e can conclude that a greater quantity of phenolic compounds wi
  • Hold an otherwise operational wireless bicycle odometer near your laptop. Watch your speed ... you just might get a ticket ;-)
  • by Aldric (642394) on Saturday July 02, 2005 @07:45PM (#12971043)
    Have you considered wrapping your lower body in tinfoil?
  • If your 2.4 GHz CPU put out any significant amount of microwave radiation cordless phone and WiFi users surely would have noticed by now.

    • Actually, mu Mum's old Panason Genius, circa early-80's (yes, it's still going!) *completely* trashes her Wi-Fi and video senders whenever it operates. My 1997 model I bought when I moved out into my flat doesn't do this.
  • Something related [slashdot.org] from a previous (ask) slashdot story.
  • Well, isn't there a metal heatsink covering the CPU? The tiny amount of microwave radiation would be absorbed by the metal heatsink unless I am missing something here.
  • Here's a cup, a magazine, and a wet nap. Don't spill. If you use Viagara, make sure you use adaquate eye protection. If it comes out green, call me in the morning.
  • Look into WiFi or mobile phone. These actually do transmit RF at > 1GHz.
  • by ONOIML8 (23262) on Saturday July 02, 2005 @11:37PM (#12971985) Homepage
    You guys are writing this off a little too quickly IMHO. I never thought about this before but I just looked across the spectrum at my Gateway 600 and....wow! It's no 40 Watt transmitter but it's sure putting out far more that I would have imagined.

    I also looked at my cell phone and my Uniden cordless phone, they don't compare. Those devices are pretty focused whereas the Gateway notebook is putting out lots more energy and across more of the spectrum. This thing is like a shotgun.

  • As an amature you will be hard pressed to measure radiation in the 2.4 GHz band. (Microwave is anything beyond 1GHz BTW.) You would need a good HP scope with high impedance probes that probably costs 100K. Better engineering universities will have this equipment. Some university profs are actually geeks so they might be willing to help if you ask nicely.

    As others have pointed out the radiation level will be quite low. Various standars have required low EM radiation.
    • Re:hard to measure (Score:3, Informative)

      by Blittzed (657028)
      I am one of the prof geeks you refer to, who works at a University and we do have the equipment to test this (ie 7GHz Spectrum Analyser), and we did exactly that when the first P4 2.4 GHz CPUs appeared a few years ago. We built an antenna tuned to the correct frequency, hooked it up to the Spec An, turned it on, pulled the case off, put the antenna in and we got... nothing. Not a peep. Zip. Buck all. This was as we expected, but we thought we'd do it anyway. So you can all put your conspiracy theories away!
  • Fertilization!
    Just have unprotected sex with your life-partner[*] as often as possible for the next 10 years. Observe whether the rate of her pregnancy goes down over the years.

    This is in no way a valid test, nor will it reveal anything about the laptop, but it'll be fun in the process, and you'll be able to claim its all in the interests of science!

    [*] Usual rules regarding STDs and ensuring you and your life partner stay true to each other, no nipping off to the local establishment to perform other not-
    • Usual rules regarding STDs and ensuring you and your life partner stay true to each other, no nipping off to the local establishment to perform other not-so-valid scientific tests with other, um, subjects

      But it wouldn't be scientific without a control group!

  • If the heat alone is a threat, It would make sense that holding a 40-watt microwave emitter in your lap could cause even more serious problems down the road.

    So, considering that you don't want to have your laptop on your lap, since it emits heat, why worry about microwaves damaging your "equipment".

    It's like saying "I am planning on ignoring this advice about the heat, but I'd like to know if there are even more threats to my health".

    My advice, don't put your laptop on your lap, treat it like a por

  • Been thinking about it for long.
    I have a CRT and non-grounded outlet.
    I know the shieldings only work when grounded, but then I also have no idea if it matters with the radiation.

    What is emitted and is it dangerous?
    Should I care?
    Should i get a TFT immediatly? (please say yes ;D)
    I could use a cord from the kitchen but uhm, no, that sucks, but I don't want to get hurt by this monitor either. Please help. This is leeloo speaking.
  • I hate to say it, but the Ghz for computers and microwaves are both measuring things in per second, but they're measuring different things. The 2.4Ghz in a computer means 2.4 billion operations per second. The 2.4 Ghz for the microwaves means 2.4 billion oscillations of the photon per second. Wait, I just realized that this is Slashdot and you all know this already. Well, at least it's out there.
    • Sorry mate, but clock speed (Hz) doesn't actually directly relate to operations per second. Case in point: the first Intel P4s were clocked higher than PIIIs but performed less opertions per cycle, and were in fact slower than the PIIIs!!! Also the reason why Athlon went to the "Performance Rating (PR)" instead of using raw clock speed.
      • Case in point: the first Intel P4s were clocked higher than PIIIs but performed less opertions per cycle, and were in fact slower than the PIIIs!!!

        Care to back that up with a source?
        • by Blittzed (657028)
          Sure do!

          The Pentium 4 performs much less work per cycle than other CPUs (such as the various Athlon or older Pentium III architectures) but the original design objective - to sacrifice instructions per clock cycle in order to achieve a greater number of cycles per second (i.e. greater frequency or clockspeed) - has been fulfilled http://en.wikipedia.org/wiki/Pentium_4 [wikipedia.org]

          And in case you aren't satisfied with that:

          As early as 2000, THG observed that the Pentium 4's performance was clearly inferior to that

    • 1 Hz = 1 cycle/second

      2GHz = 2.4 billion cycles/second

      The GHz is measuring EXACTLY the same thing

      Just FYI, the skin depth of a 2.4GHz EM wave should be on the order of 50nm - the heat sink alone should be more than enough to stop virtually all microwave radiation from your laptop

  • Zapchecker (Score:3, Interesting)

    by AeiwiMaster (20560) on Monday July 04, 2005 @05:09AM (#12978283)
    Get yourself a zapchecker [zapchecker.com]

    Mine shows some radiation form my computer.
  • The 2.4GHz clock is generated inside the CPU, multiplied up from the external clock by a PLL. A few microwatts may get out, but it's just RF. All it can do is heat things up. Your balls are already being cooked by conducted heat, so don't worry about the RF.
  • To be sold in the US, the laptop has to pass FCC certification- there are similar requirements for every other country. The FCC requires that emissions be below a certain level, so that they don't interfere with legitamate users of the airwaves- so there has been testing that has shown that the power level out is pretty low (usually in the microwatts or lower).

    But the biggest reason why I wouldn't be concerned is simply the conservation of energy- all of the energy in the laptop is consumed some way- ulti

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