Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

A Tazer

  1. Jun 16, 2004 #1
    I don't understand how these tasers that have 50,000V only produce a very low amperage. According to Ohm's law that should kill you. Voltage divided by the persons resistance (Ohms).
    Getting shocked by static electricity has 5000V, but doesn't kill you because there is no circuit involved, just the transfer of electrons to your finger, or whatever touched the metal. I understand that.
    But when you get zapped by a taser isn't this capacitor discharging through your body, thus creating a circuit?
  2. jcsd
  3. Jun 16, 2004 #2
    The voltage is stepped up through transformers. Remember you can't get something for nothing so the power output always stays the same. When the transformers increase the voltage, the current drops...thus conservation of energy wins again! And remember the circuit is only through a small portion of the skin between the two metal pins. But the voltage jolt still hits your system enough to stun you.
  4. Jul 9, 2004 #3
    I=V/R .. only if VI <Pmax

    You can't use the OHM's LAW relationship with 2 knowns to find one unknown with Tazers and similar phenomena because the VOLTAGE is not constant. The Voltage drops like a rock once current goes up. So it's not a linear relationship. A powersupply operating within it's current limits obeys a LINEAR ohm's law.. upto that limit

    For example, a 1pF cap charged to 100V (if possible)... only has a small amount of energy in it.. thus it can't sustain that 100V when current goes up. The voltage will drop like a rock. It's all about energy... if the energy demand (an assumed constant V mulitiplied by the I) is within the maximum Power limit, then u can assume a constant V.

    I'm making a big deal about this because I've had so many people ask me questions like this. I remember a group of people at work who were saying "The people over at the ESD department are stupid, there is no way a human body can charge to thousands of volts." OR "ISn't is cheaper to amplify with transformers instead of amplifiers circuits?"
    Last edited: Jul 9, 2004
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook