What is the energy stored in a taser? Can you se 0.5*C*V^2?

[tsuwal]

How does a taser work? If it is a bunch os condensers that discharche, the energy would released would be 0.5*C*V^2. I'm asking this because I say in a movie a taser being discharged metal necklace. The necklace would have short-circuited and warmed a lot, right? Probably making a severe burn or something. What do you think?

 

[Drakkith]

By condenser, do you mean a capacitor?
And I believe the energy is stored in batteries which charge capacitors in the taser.
As for the metal necklace heating up, I don't think a taser can supply much sustained current, as I believe most are designed to "pulse" in a certain way that interferes with the brains ability to communicate with muscles, thus incapacitating the victim while they are being tased.

 

[berkeman]

How does a taser work? If it is a bunch os condensers that discharche, the energy would released would be 0.5*C*V^2. I'm asking this because I say in a movie a taser being discharged metal necklace. The necklace would have short-circuited and warmed a lot, right? Probably making a severe burn or something. What do you think?

If you use Google Images to search for Taser Gun Circuit, you can see what the basic circuits are. They are high voltage pump circuits, and don't rely much on storing energy on capacitors.

I don't know what happens when you short the output of a Taser, but probably not much. It would likely go into current limit, and not deliver much power. Don't believe everything you see in the movies!


EDIT -- Beat out by the space fighter jockey!

 

[tsuwal]

**Errata: yes, i meant capacitors.

I've seen that it uses a voltage of 80.000 V and is supplied by a battery of 9 V. The battery can be used 50 times, so assuming the battery has a capacity of 2000 mAh, iy supplies about 100 C each time. 100 C * 80 000 V = 8 MJ ?! This value is very high, but even assuming that it is a pulse and not DC, say, 1000 less, its still 8 kJ!

 

[Drakkith]

How are you arriving at the 100 C? That's a LOT of current. The equivalent of 100 amps over 1 second, a number which seems absurdly high.

 

[berkeman]

How are you arriving at the 100 C? That's a LOT of current. The equivalent of 100 amps over 1 second, a number which seems absurdly high.

Agreed. I doubt if the output current is more than a few mA at [STRIKE]80kV[/STRIKE] 5kV. Don't want to kill the person, after all.

 

[berkeman]

**Errata: yes, i meant capacitors.

I've seen that it uses a voltage of 80.000 V

Where did you read this. I checked the TASER website, and they say it is 5kV...

http://www.taser.com/research-and-safety/how-a-taser-works

.

 

[d3mm]

You are correct when you say that covering yourself with tin foil will protect you from a taser by creating a short. The charge will then be transferred through the operator but not in manner that would harm the operator.

[STRIKE]When shorted, [/STRIKE]there isn't enough energy to cause painful heating. The pain is caused by electric interference with the nerves.