What's the difference between Volts and Amps?

Discussion in 'General Electronics Chat' started by CD-RW, Feb 28, 2011.

  1. CD-RW

    Thread Starter Member

    Feb 26, 2011
    Can anyone please tell me what the difference is between the following two sources:

    a) 10vdc @ 1A

    b) 10,000vdc 0.001A

    If we compare the two sources with each other, in the first example the voltage is 1000 times less, and the amperage is 1000 greater.

    In the second example the voltage is 1000 times greater, and the amperage is 1000 less.

    So if we use the formula W = V x A for the above two example sources:

    10v x 1A = 10 watts

    10,000v x 0.001A = 10 watts

    Is the total power output the same for these two sources?

    And if so, why is it that example b) would give you a perceivable nasty shock, :eek: whereas for example a) you'd probably not even notice anything?:D

  2. davebee

    Well-Known Member

    Oct 22, 2008
    The difference is like comparing a bullet (high speed, low mass) with a thrown baseball (lower speed but higher mass).

    While the power may be the same, voltage and current have quite different properties, much like the baseball and the bullet.

    As you note, the higher voltage is much more dangerous to people, because of its ability to drive current through a higher resistance.

    But the higher current, while safer, will usually lose more power in the wires, so low voltage, high current may be less desirable for that reason.
  3. nomurphy

    AAC Fanatic!

    Aug 8, 2005
    Volts are the electro-motive force or the potential to move electrons, it is the energy to move electrons through a conductor.

    Amps is a measurement of the amount of electrons that are moving through the conductor; a Coulomb is 6.28 x 10^18 electrons, where 1 Coulomb in 1 sec = 1 amp.
    1V x 1A = 1W (dissipated power)

    My question for you: Is it just coincidental that 6.28 is essentially 2pi?
  4. CD-RW

    Thread Starter Member

    Feb 26, 2011
    Thanks Dave.

    Are you saying that electrons travel at a higher speed the higher the voltages are?
  5. debjit625

    Well-Known Member

    Apr 17, 2010

    Think like this current is flow of something and its the flow of electrons i.e.. the electrons is moving threw the circuit now these electrons cant move by them self they need some sort of force(pressure) to make them move within the circuit and this force is known as voltage.Now in example "b" we have a very huge force 10000V and this cause current to flow threw our body very easily but in case of "a" the force is too small and the current cant move so easily threw our body and we dont get a shock.

    This was a very small and incomplete details about electricity if you really want to know more, this site have a very good free ebook that can help you the most ,above on this web page you will find the links to the ebook,start with VOL 1 DC : http://www.allaboutcircuits.com/vol_1/index.html
  6. davebee

    Well-Known Member

    Oct 22, 2008
    Probably, but not necessarily; the analogy is not that direct.

    Voltage is a measure of the electric force that accelerates the electrons.

    Current is the measure of the overall flow of electrons.

    What actually happens is that electrons accelerate due to the electric field, so they build up speed until they slam into a molecule or something, losing their energy as heat, then they accelerate again.

    With a more powerful voltage, the more powerful electric field probably will generate more average speed overall, as well as it may simply get more electrons to move, resulting on an overall greater current.
  7. CD-RW

    Thread Starter Member

    Feb 26, 2011
    Thanks, I have the whole 6 volumes downloaded from Tony's website.

    This looks good, but it's timing out ATM:

    What is Voltage?
    Of several electricity concepts, the idea of "voltage" or "electrical potential" is probably the hardest to understand.

    It's also really tough to explain. It's a headache for both the student and the teacher. <GRIN!> To understand voltage, it helps if you first understand a little about its nearest relative, magnetism.

  8. K7GUH


    Jan 28, 2011
    An analogy, but a useful one. Volts are like water pressure; a small drip or a weak flow wouldn't hurt you, but a high pressure fire hose will knock you flat, and may cause you serious injury. Amps are analogous to volume of water flowing. A small flow will simply get you wet; a larger one might be enough to drown you; a huge flow, like a tidal wave, doesn't have much pressure, but sure has the momentum to knock everything over. And over, and over.
  9. mrscrewdriver

    New Member

    Dec 2, 2007
    a) 10Watts
    b) 10Kwatts
  10. Adjuster

    Well-Known Member

    Dec 26, 2010
    Where do you get 10kW from?
  11. Barnaby Walters


    Mar 2, 2011
    That's the beautiful thing about maths… It's a way of thinking that humans believe we've invented, but there are so many things like 6.28 = 2pi that seem 'intentional' in some way :)