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Everything posted by mmalluck

  1. Current flowing through the body is a bad thing. It manifest itself as the misfiring of nerve impulses causing muscle spasms and pain. At higher voltage and current levels the flesh itself begins to cook. You'll definatly feel that one.
  2. I'm a recent EE grad and looking for work. I'm spent the past year working on a academic research grant, but now it's time to find a real job. Anyone out there have interested (or have contacts interested) in hiring a EE with interest in power and e-mag out on the west coast or south-east (USA)?
  3. And he also says "What happens if you remove the appliance/resitor from that circuit" If you remove the load (open the circuit) the current can not continue to flow. Current depends on the voltage and load. The circuit can not 'be left intact' with the removal of the load. Remember: V=I/R With wall sockets, the voltage is constant. As such, it's better to look at what the current is doing when we vary the load. so.... I = V/R So are you asking what would happen if you yanked the plug out of the wall while the lamp was on? or about jabbing forks into the electric socket? The first one would result in nothing drastic. The removal of the load (our lamp) would see that the resistance across our circuit approaches infinity. Going back to our equation: I = V/R, we'll assume your on a 120v circuit, so yanking out the lamp would look something like... I = (120 volts / Near Infinite Ohms), so no current will flow. The second (jabbing a fork into the socket) would lead to a blown fuse or tripped circuit breaker. The fork looks like a load resistance of zero ohms (nearly). I = (120 volts / nearly 0 Ohms), so tons of current flows. Now in electrical circuits, current is directly related to the power the circuit consumes Power = Current * Voltage P= I*V We have a high current, a fixed voltage, so that fork will be drawing lots of power and the fork will give off this power as heat. If the circuit breaker doesn't trip, nor the fuse blows, you'll end up with a smoldering fork or wall wiring.
  4. Dielectric lenses can be used to direct and focus all forms of electromagnetic radiation. Here's an example of microwave lenses being used with horn antennas: http://www.flann.com/Products_Home/Antennas/Lens_Horn/lens_horn.html The actual lens is the white disk filling the inside of the horn. Alpha and Beta particles are not EM radiation and therefore can not be forcused with a lens. The important part of the lens is the geometery and the dielectric constant of the material used. The constant determines how much the wave is defracted while passing through the material. A little math' date=' some materials data, and some skill with shaping plastics and you can make a lens for any wavelength. If your box is used here on earth (which I'm 99.999999999% sure it is), your best bet is visable light and/or IR and UV. It's the greatest form of radiation present, with a wavelength thats easy to work with. Almost all x-ray and gamma ray radiation coming from the sun is attentiated by the atmosphere. Also, most people don't appreciate having x-ray or gamma-ray sources pointed at them. Cancer sucks. Microwaves and radiowaves would require a huge hole (more than a few wavelength across or you'll end up with the age-old single-slit experiment) for your pin-hole camera to work, as well as, a huge backplane to capture your signal with any decent resolution. We're talking about antenna arrays the size of football feilds. Not something you can really build. For instance frequency of 2.4 Ghz equates to a wave with a wavelength of 12cm. Your hole should probably be at least 36cm across. Take your pinhole camera and scale up the size of it, so that it's hole is 36 cm across and you'll see you have a huge honking camera. As far a sensors go' date=' I'd get me some little IR detectors or photo transitors. Most light sensors will work over a range of frequencies with decreased sensitivity, but they'll work all the same. If you want something really cool, try getting your hands on the IR sensor (tube) out of a nightvision scopes. IR comes in one end, visible light comes out the other. You could just buy a ccd and build your own ccd based camera. or buy something cool like this: http://www-2.cs.cmu.edu/~cmucam/ Not true. Inexpensive webcams can be turned into nightvision scopes by merely striping off the IR blocking coating on the lens. true, this type of IR is not heat based, but it still is pretty cool. http://www.mobile-review.com/forum2/showthread.php?t=29672 I seriously doubt you're going to be able to build anything that can see through walls, cardboard, or even sheets of paper. If it were that easy then everyone would have bought/built one.
  5. Won't disolved CO2 be evident with the use of Lithmus paper or brothel thymol blue? I remember Mr. Wizard (years ago) doing something like that. Blowing through a straw into water changed it's color. CO2 made the water slightly acidic. This is also why flat softdrinks often taste sweeter than their carbonated counterparts. The acidic nature and taste of the CO2 is masked by the use of more sugar. This is also true of seltzer water, but there's no sugar to begin with.
  6. Remind me to not go out drinking with Dak....
  7. No more than light or any other EM wave. Gravity-wells (planets, stars, blackholes) are known to bend space and therefore the travel of EM waves around them. As long as a blackhole isn't directly between your reciever and transmitter you'll probably be okay. Gravity-wells can also help. In certain cirmustances, blackholes and the like are able to bend space into a magnifying lense of sorts. These are often refered to as gravity-lenses. Here's a link that talks about light distortion due to gravity-wells and the lenseing effect it can cause: http://www.suite101.com/article.cfm/astronomy_astrophysics/110308
  8. Air is still matter. Sure it does a lousy job of blocking radiowaves, but given enough of it, it will attenuate the signal off to nothing. Also there's a lot of radio noise sources here on Earth that will 'hide' a signal as it becomes weaker. Outerspace on the other hand is filled with mind-boggiling amounts of nothing. The waves will propigate unobstructed and there are very few noise sources in space. I imagine clouds of dust, like nebulas, would interfer with radiowaves as would interference from the sun (random solar flares and the like).
  9. A cockroach can live as long as two weeks without it's head. The Orkin-man told me so...
  10. A plasm, by definition, is cloud of positive and negative ions, and as such they are influenced by a magnetic fields. Fusion reactors, like the tokamak design, use a magnetic bottle to contain the ultra-hot plasma, that would otherwise be bad for the surfaces of the reactor. Google turned up this links. Look them over. http://www.fusion-eur.org/fusion_cd/magnetic.htm http://library.thinkquest.org/17940/texts/magnetic_confinement/magnetic_confinement.html
  11. Anything with a metabolism will generate heat; bateria, monkeys, your mom. Even an egg has it's own body-heat, the problem is it can't substain it without help.
  12. Silver solder is the king of pipe joints, but the higher melting tempreature (430 degrees to over 1300 degrees F) make it rather prohibitive to use with electronics. All those little junctions in semiconductor chips don't like heat too much. The less heat you use, the less chance you'll cook the chip.
  13. mmalluck

    ice bomb?

    What if you used a large tank of LN2 and dropped it from a plane? The explosive decompression of the gas will draw a lot of heat out of the enviroment. Sure, it's not a truely chemical explosion, but it would be closer to the desired affect.
  14. Think about the silicon ingots that are cut up into waffers for computer chip production. Each ingot is a single crystal with purities measured in realm of less than one part contanimant per billion atoms. That makes for one huge molecule! Make your own silicon with this webpage
  15. Okay there's a couple of reason why hybrids are more efficient than a regular gas engine. 1. The energy from braking can be converted back into electricity and used to recharge the batteries. This is referred to regenerative braking. Regular cars just use frictional braking and all the energy is wasted as heat. 2. The torque curves of an electric motor and gas engine compliment each other. Electric motors supply the most torque at low RPMs. Gas engines supply the most torque when they are in their 'power band'. This is usually at several 1000 rpm. By using a properly designed gas/electric hybrid you can have a total system output with a much larger power band. This means you use each motor at the points where it supplies the most power at the greatest efficiency. The electric motor gets you off the line quickly, but the gas engine carries you when you're cruising along. 3. If you cheat and use a wall socket to occasionally top off your battery, you win twice over. Gas engines are horribly inefficient if you look at the chemical energy of the gas compared to the output of the engine. Most of that energy goes off as heat. Power plants, on the other hand, are very efficient at converting chemical energy into electricity. If you use the energy derived from a power plant to charge your battery every now and then, it'll cost less than the gas you'd use, and it'll be derived from a much more efficient source.
  16. Tom Cruise is a nut-job. He can use his stardom to attract attention to the possible problem of the over-medication of America, but in no way is he qualified to make any judgement. In closing, I leave you with this....
  17. Well lets see.... It's rated for a maxium of 220vac and you decided to run it at 240vac. Not to surprising it died really.... I'm guessing this is an electrolytic and most (but not all) are polarized. This means one terminal needs to be keep positive and the other terminal negative with respect to eachother. Things like camera flash capacitors and what-not usually have a dark stripe with little negative signs to denote the negative terminal of the capacitor. Failing to hook it up right will end with a lot of smoke, goo, and possibly rupture.
  18. If I was acting as the government and looking at these possible options: 1. Doing nothing 2. Setting off an EMP 3. Sending in special agents I'd go with 3. If we set off an EMP at the very best most electronics are destoryed and at the worse the EMP sets off the nuke itself. If either of those happen, you're going to have a ton of people complaining one way or another. With unhappy people come protest and possibly riots. Not pretty. With 3 you may stop the nuke and if so you're the hero. Nothing is broken and people love the government. If you fail you can deny ever knowing anything about it in the first place and blame the terrorist. You rally the people to your cause and go to war. By the time anyone figures out the goverment knew anything in the first place, the point is moot. Seems like the best option for the government, but not nessarily the people.
  19. Nor are all the electronic devices in the area where a dirty-nuke could be used. Would it be worth nocking out most of the electronic devices in a larger metropolitian area, to disable a dirty-nuke? What if the emp is just as likely to set off an improvised dirty-bomb/nuke? Doesn't seem like a good idea to me.
  20. Could the 'Big bang' be seen as the formation of a white hole? What if the unexplainable accleration seen in our universe is due to matter falling into blackholes in a parallel universe (IE, the more matter a black hole in a parellel universe is feed, the faster the white hole, which is our entire universe, expands)? Yes, just unfounded speculation, but fun ideas never the less.
  21. You could expand this topic to even a broader, more generic categories of "good vs. bad". The human mind likes simplicity and these are the most basic of categories. All things that help and individual or the individual identifies with are sorted into "good". All things the individual fails to identify with or are found to be harmful get sorted into "bad". People and cultures falling into the "bad" category are usually de-humanized so that when conflict arises, the individual can go about disposing of the "bad" and avoid internal conflict. For example, look at the propaganda from any war and look at how the enemy is portrayed.
  22. I'd venture to say greed and selfishness are inhert to all life, from monkeys to bacteria. What species, given nearly endless resources, won't grow out of control until the resources become a limiting factor? None and humans are no exception, though you may say we should know better.
  23. If thats true than the moon contributes 2.2 times as much force to the tides as compared to the sun. So with no moon, tides will crest 2.2 times lower, right?
  24. I'm curious to how much the sun contributes to the tides. Is this the right way to go about it???? The moon weighs 7.35 x 10^22 kg and is 384 * 10^3 km away. The sun weighs 1.99 x 10^30 kg and is 150 x 10^6 km away. The earth weighs 5.976 x 10^24 kilograms Gravity falls of by a factor of 4 every time you double the distance between two bodies or in other words it follows x : 1/x^2 relationship. Gravity is directly proporinal to the weight of an object (x : x). From this we get the equation: (F) = (Mm)/r^2 The force exerted on the earth by the moon is: (5.976 x 10^24 kg) * (7.35 x 10^22 kg) / (384 * 10^3 km)^2 or 2.978 * 10^36 kg^2 / Km^2 The force exerted on the earth by the sun is: (5.976 x 10^24 kg) * (1.99 x 10^30 kg) /(150 x 10^6 km)^2 or 5.28544 * 10^38 kg^2 / Km^2 So the sun exerts 177 times more force on the earth (and presumable the tides) than the moon? I though the moon was the major contributer to the tides. The moon causes a buldge of water to form on the earth due to it's gravitational pull (read:tides). No moon -> smaller buldge -> more water elsewhere. Again this wouldn't mean a very drastic change in ocean level.
  25. 1 g is not a velocity!!! It's an acceleration! I think that's where you're confused flyboy. A g = 9.8 m/s^2 which is the force equivalent to that of the earths gravity. If we accelerate with an acceleration of 1 g, our little astronauts will be forced against the back of the ship with a force the same as the earths gravity. That is to say, that if our astronaut stepped on a scale he would weigh the same as he does on earth. After one second we'd be traveling with a speed(velocity) of 9.8 m/s After two seconds we'd be traveling with a speed(velocity) of 19.6 m/s After three seconds we'd be traveling with a speed(velocity) of 29.4 m/s After four seconds we'd be traveling with a speed(velocity) of 32.9 m/s and so on.... If we start accelerating with an acceleration of 2 g (19.6 m/s^2) and our astronaut again steps on a scale, he would weigh twice as much as he does on earth. After one second we'd be traveling with a speed(velocity) of 19.6 m/s After two seconds we'd be traveling with a speed(velocity) of 39.2 m/s After three seconds we'd be traveling with a speed(velocity) of 58.8 m/s After four seconds we'd be traveling with a speed(velocity) of 78.4 m/s and so on.... If we accelerate too quickly and our astronaut will experience too many Gs and will be crushed by his own weight. It's true. I could be going million trillion quazillion billion m/s (excuse me while I rip a hole in the space-time continuum as I travel faster than light ) and it's true I wouldn't feel any thing, but if I try to speed up to that ludicrous speed in a second from a stand-still, I'd be squashed all over the inside of my spaceship. That's funny. Your link just goes back to this thread.
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