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High Voltage or High Amperage ?

  1. Nov 14, 2013 #1
    Hey everyone, I wish to spark no heated debate, but is it possible, to have a flow of electriciy with a high voltage amount but at low amps? Or vice versa, low voltage but very high amps?

    What would need such dis-proportioned measurements?

    And finally, which would be more deadly. Is touching something with a high voltage, but only push a small amount of amps still more dangerous than something with a lot of amps but a very low voltage?
  2. jcsd
  3. Nov 14, 2013 #2
    The short and simple answer to your 3ed question is that more amps are more dangerous, a household outlet at say 20 amps and 110 volts is more likely to kill you then say an electric fence at .01 amps and 20,000 volts.
    Ps. Both hurt a lot.
  4. Nov 14, 2013 #3


    User Avatar


    Yeah, such be the case...






    If you've read them... disregard.

    Neat video, though...

    Oh, BTW... check out the Z machine.

    The picture is worth a look, at least...

    Also, somewhat interesting...


    Last edited by a moderator: Sep 25, 2014
  5. Nov 15, 2013 #4
    Yes it's possible. Examples of high voltage and low current is mentioned above. Example of low voltage but high current is impulse current generators.

    a) high voltage and low current

    Electrical equipment (e.g. transformers) are subjected to overvoltages that are caused by switchings in electrical circuit, voltage surges owing to lightning strikes in transmission lines and other reasons. Its ability to withstand such overvoltages have to be tested and people use different high voltage generators for this purpose.

    b) low voltage and high current

    Sometimes in electrical network occur short circuits due to erroneous switchings, animals that touch two wires and other reasons. Its an emergency state of operation of electrical network, because current is higher than it have to be and network have to be switched off. A circuit breaker performs a clearing of electrical network. Its ability to do this also have to be tested.

    I think that impact on one health depends on a power of a source, because it determines current flowing through the body (current is also determined by resistance of the body that depend on a state of skin, frequency of current and other factors). One could get high current with a low power source and if one connected this source to the body current would be low. It is current that determine the impact on one health (and also a path of current inside the body, frequency of current, a time of exposure to current and other factors). For example, current above 100 mA (50 Hz) causes fibrillation (one can take resistance of the body equal to or greater than 1 kOhm).
    Last edited: Nov 15, 2013
  6. Nov 18, 2013 #5
    Ever take a spark plug out of one of your cars' cylinders and, while still attached to the wire, accidentally touch it while the car is started while attempting to "test" it (check for spark)? I mean just touching the wire itself where the spark plug plugs into (not the actual plug.. don't try this at home!)? You'll know high voltage vs. low amps real quick (spark plugs are at 20,000volts up to 100,000volts). Or a fluorescent light ballast which runs off of dc battery voltage which needs to change 12 volts up to 500+ volts. Important to keep in mind that batteries have their own internal resistance!

    Your body is not a great conductor (assuming you didn't just get out of the shower) as Cyril above said. But it is made up significantly of water. So it does conduct but has some varying resistance depending on water on your skin, etc. . As Iwant2beoz pointed out, it is current which is what does the damage. Current means it's moving around the atoms in your body (or parts of them). That's not good. If your body had a huge resistance by some means, then megavolts wouldn't cause current to flow (in theory I mean).

    Amps = Voltage / Resistance. Less voltage = less amps per resistance. More voltage but more resistance equals lesser amps. The key in understanding is ohm's law(s).

    And personally I'd rather get shocked by dc than ac from experience. Edison may have agreed (he killed a dog for show using ac to prove Tesla's ac more dangerous). High voltage dc (battery... which has resistance) feels just as bad as 120vac (~170 peak)vac. They say the ac is "better" because it crosses 0volts 60 times per second. But it's also pushing and pulling your atoms as opposed to dc. Just my personal experience at being shocked a few times. The dc voltage was always battery source which has resistance so if the dc was actually low impedance I'd probably say otherwise (i.e. I'm speculating).

    The bottom line is voltage is merely potential energy. If a piano is hanging by a wire, and you are under it when it falls... you're in trouble.. assuming it is large enough (i.e. can overcome your resistance). If you are at the same potential energy as the piano (standing on a surface same as its height... i.e. voltage reference) you'll be ok.
    Last edited: Nov 18, 2013
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