Hello!I have lots of questions:1) I've heard the a car battery can generate 12V @ 500A (6000W [or am I wrong?])! If I try to power my Arduino with this power (not that I'm gonna), or simply touch the terminals with my hands, will I get hurt?A car battery will only supply such peak currents for a few seconds before the voltage will sag. And no you will not be shocked from a 12vdc source voltage. However if you were to say short circuit a car battery across a metal wristwatch band you were wearing is could turn near incandescent and burn you severely.2) That means that you can use a transformer to step up the power to 110V @ 54A from a car battery?No, a transformer can pass only AC voltages not DC voltages. And as said a car battery will not supply 500 amps for more then a few seconds.3) What is the amperage of mains power in Canada?It's limited in the size of the main and distribution circuit breakers installed in your home service box. Here in US most are limited to 200amps total and most circuit branches are limited by 15, 20, or 30 amp branch circuit breakers.4) Why does the green box transformer in the neighborhood vibrate and hum?Not sure what kind of transformer you are describing, but AC power runs at either 50 or 60 hz in most countries and that can be heard if it causes the transformer winding to mechanical vibrate in the transformer metal core.5) What is inductance? Is it electromagnetism, or "inducing" a current in another coil using EM?Current flowing in a wire cause a magnetic field to be developed, or imposing a changing magnetic field to a wire will cause a changing current to flow in the wire. Best to study basic AC theory to get a better understanding of induction and capacitance.6) How does an inductance charger induce a current in a toothbrush if there is no return path for electrons?It's basically just a transformer AC coupled power circuit and there is no requirement for a DC return path as the transformer secondary winding inside the toothbrush allows a current to flow because of the magnetic field coupling the primary and secondary windings.7) Will this cause the same amount of damage to a human: 110V @ 15A, 500V @ 3.3A, 1650V @ 1A, 82500V @ 0.02A (they are all 1650W [V * A])?The higher the voltage the higher the shock risk to personal. The amount of current to flow through a human is dependent on the resistance of the path through the human and obeys Ohm's law as to how much current will flow. Current is not 'forced' it is 'drawn' by a load resistance following ohms law. Because a voltage source has a maximum capacity of say 15amps does not mean every load will draw 15 amps. Study ohms law to understand the relationship of voltage, current, and resistance. Should this be posted under bar sport or general discussion?Doesn't matter to me, I just scan 'all new posts' and rarely even read what subsection it's posted in. But then again I'm not a moderator that is tasked to care about such things. 9) If mains power's ground (reference point) is the Earth, and reference points are usually the negative terminal, would electrons be drawn out of the Earth (a current is draw out of the - terminal of the battery, and returns to the + terminal)?No. First, mains power does not have negative and positive terminals as it's AC not DC voltage. Only DC voltage sources have fixed positive and negative terminals. Earth ground is often used as a common point to wire all ground wires together at one central point in AC power systems, however there is no current flowing into or out of the earth. Grounding can be a very complex subject and easy to misunderstand. But there is no requirement for a true 'earth ground' for current flow in circuits.10) If static shocks are 10000V+, does static electricity have an amperage or wattage?Yes if there is a current path for the voltage to flow, but the voltage alone does not provide enough information to calculate the amount of current flowing in such a case. Joules is a more common metric used in characterizing static short term voltage discharges rather then wattage. Again current can only flow in a complete circuit and the amount of current is depended of the resistance of the circuit path. Voltage alone does not provide enough information to analyze circuit performance. Ohm's law dictates the relationship between voltage, current, and resistance. You must know two of the terms to calculate the third term. 11) What's you're opinion on this: http://amasci.com/emotor/nostat.html ?Not really very educational, seems more rather a 'rant' about terms used. Static electrical properties are well understood by industry, so I don't really get the authors point or concerns.12) Does the Earth have to be a good conductor to be a reference point for electricity?No. A battery powered radio does not require a earth ground, so for electronics circuits to function do not depend of earth. Earth grounding is usually only important for allowing a high current path for lighting protection. Don't confuse circuit common connections with earth grounding connections. They are sometimes the same physical connection as in house AC power input wiring, but having the circuit common wired to a grounding rod is not a requirement for circuit operation but rather as a safety requirement.Fact: "Currents are often regarded as flowing from + to -; a legacy of ancient misunderstandings." - quote from a book.That is a ancient argument of what direction electricity flows in a DC circuit. Electricity theory predated the knowledge of the basic atom structure, so they didn't even understand about electrons being the current carrier in a conductor even though they knew that something was flowing. So they stated and agreed that current flowed from positive to negative. Today we know that electrons flow from atom to atom from negative to positive charged atoms. So ever sense we have to live with the awkward statement that current and electrons flow is in opposite directions. They even came up with the concept of 'hole flow' to try and fix the discordant. It doesn't matter in the big picture but electron flow (negative to positive) is the more accurate explanation in my opinion.Thanks!
Current is not 'forced' it is 'drawn' by a load resistance following ohms law.
No, a transformer can pass only AC voltages not DC voltages.
Grounding is a confusing topic: http://arduino.cc/forum/index.php/topic,104134.0.htmlI still don't really get why if you touch a bare high voltage wire while standing on the floor, why do you get hurt? Where's the return path for electrons? Another grounding issue!Yes, if you feel a shock then there is enough current flow to cause it. There are few 'perfect insulators' if the applied voltage is high enough. Even air is not a perfect insulator or else there would be no such thing as lightning bolts.QuoteCurrent is not 'forced' it is 'drawn' by a load resistance following ohms law.What happens when a load draws more current than the source can provide (e.g. short circuits, 3V @ 380mA motor)?Every real voltage source has some internal resistance value that will limit the maximum short circuit current that can flow even into (and especially) a 'perfect' short circuit. So ohm's law still governs the situation.Thanks for answering my questions!
I still don't get why if you stand on the Earth and touch to high voltage wire, you get hurt. That means that electricity surges through you! I'm not so concerned about resistance here. Where's the return path (or is there)?
And yes the ground is an insulator but not the water that is available in the ground.
So that means that I am connected to power plant via the water in the Earth? Sorry, grounding+insulation still has me confused (there is enough water in the Earth to conduct to the power plant?).
Also, why does my iPod charger release some sound that sounds like a cross between clicking and humming all the time when plugged in, and emits a high EMF measured by my Arduino EMF Detector, compared to other transformers (chargers)?
Why are some plugs for appliances "polarized" (one lead bigger than the other) when AC is supposed to have no defined terminals?
Is the word "lead" (as in leads (terminals) of a battery) pronounced like the present tense verb of "leader" (as in "to lead"), or as in the toxic metal lead?
Can you safely measure mains voltage using a multimeter set to 200Vac?
http://en.wikipedia.org/wiki/Mains_electricityI think that I get how the power outlet in my house works. The small socket is at 0V potential (neutral), the big socket is a 60Hz sine wave of -110V to 110V and the round socket is connected to the Earth, as a safety precaution to lower the risk of electric shock, shorts, etc. (I think).
Please enter a valid email to subscribe
We need to confirm your email address.
To complete the subscription, please click the link in the
email we just sent you.
Thank you for subscribing!
via Egeo 16