How can electric fences have a high voltage and low current when current is proportional to voltage?

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As I understand it, voltage is the difference in charge between two points. The greater that difference, the greater the current because more electrons will flow between the two points.

I thought a high resistance might explain this, but apparently the metal in electric fences have very low resistance.

In: Physics

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Anonymous 0 Comments

They don’t have low current. It’s that simple, you’ve been lied to.

The secret behind electric fence, tasers, and that doorknob that was whopping 10 kV and inconveniently stung a little is TIME. Not low current. The current is high. The time it existed for is tiny. This limits the damage done and energy unloaded on you.

Now, with a static shock, it’s clear that it is a very short duration. But aren’t tasers and electric fences a constant shock? No. They just pulse on and off really fast with short durations and a duty cycle that is mostly off.

Now, you could describe the time average current as being low. Which despite the high peaks, the long times off results in a low time average current. However, that’s misleading to do that to current, but not voltage. The voltage peaks are high before contacting, but quickly decay so also exist for a very short time. If you time average the voltage, it’s also low. But doing that is a problem, as a low voltage can’t arc or anything and high voltage can exist steady state before making contact at a high value no issue, so you need the high peak voltages to explain that.

Hence, your confusion. A high peak voltage and a low time averaged current is what you have been told, but this is a highly misleading way to state it if you drop to clarifications and confuses anyone familiar with ohms law (rightfully so).

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