/sci/ - Science & Math

[Anonymous No.9671855]

What is it about the human body that makes it a good capacitor?

Its rated at 10 picoFarads but seems to have unlimited potential for voltage?

https://www.youtube.com/watch?v=oKjgFdtSP9E

This guy stands on a plate to insulate himself from the ground. Then charges his body up to high voltage ratings to perform tricks.

Why don't we have advanced circuits based around using the human body?

[Anonymous No.9671906]

>>9671855
Because the human body isn't a very good capacitor.
He's only able to reach a substantial voltage because of the insulating plate.
A chunk of steak would be about as useful in a circuit.

[Anonymous No.9671947]

>>9671906
How does he not kill himself when he grounds? What controls the flow out?

[Anonymous No.9672459]

>>9671947
The body is a relatively high impedance path though it varies a lot based on exact physical dimensions, makeup of the body (eg. ratio of fat to muscle which likely have different conductances per unit area), whether the skin is dry, wet, sweaty, etc.

The human body is a very complex and highly variable RLC circuit that is very difficult to model in any precise terms though there are some general approximations of the impedance for an average person given particular conditions.

>How does he not kill himself when he grounds?
Consider the capacitor stored energy equation:
U=(1/2)*C*V^2 given C = 10pF and V = 200kV. U = (1/2)(10^-12)(200^3)^2
U = 20mJ. It's fucking nothing.

It's very likely that he could only be charged to 200kV when there was effectively an open circuit between himself and ground. As soon as he touched anything with a connection to ground the voltage was probably clamped down to a much lower value. With such a small amount of energy stored in this human capacitor even a leakage current of a few μA could be enough to clamp the voltage down to well below lethal levels.

[Anonymous No.9672489]

>>9671855
water and salt

[Anonymous No.9672846]

>>9671855
>good capacitor
>10 picoFarads
L0Lno fgt pls

[Anonymous No.9672857]

>>9672846
There's no such thing as a good or bad capacitor. Small caps in the picofarad range have plenty of applications as do large caps in the range of 100s of microfarad.

You'd never use something like a 10pF cap for something like power supply filtering but they're used for stabilizing crystal and ceramic oscillators. Small caps are also used in the designs of passive filters and highly selective crystal ladder filters, for timing of some relaxation oscillators, for bootstrapping in amplifiers to increase bandwidth, any many more applications. So no a 10pF similarly small cap is not a "bad" cap. It's bad if you use it in the wrong application but they are plenty useful in the right applications.

[Anonymous No.9673280]

>>9672846
>>9672459
>>9672857
OP is mistaken on human rating. Its 100 pF, not much better, but not 10.

[Anonymous No.9673321]

>>9673280
>capacitor stored energy equation
200,000 volts with 100pF is 2 Joules of energy or a 20u Coulombs charge.

[Anonymous No.9673355]

>>9673321
Oops sorry last samefagging. It you assume it takes .1 second to discharge this is 20 watts.
20 watts at 200,000 volts is 0.001 amps.

Even if he doubled the volts. 400,000v would by 8 joules of stored energy, will discharge with 40 watts, and the amps is even lower at 0.0001.

1 Million Volts at 100 pF is 40 joules , 400 watts, 0.0004 amps

A slow charge to these levels will never kill you if you magicked a way for it not to ground during the charge.

The reason why lightning kills you is because they are about 5000 to 10000 amps.

[Anonymous No.9674308]

>>9673355
Bullshit, current doesn't kill you, voltage does.

[Anonymous No.9674381]

>>9674308
Your post gave me cancer. Never post about electric circuits again.

[Anonymous No.9675172]

>>9674308
Literally retarded

[Anonymous No.9675227]

>>9672857
>There's no such thing as a good or bad capacitor.
Five hundred thousand technicians and engineers disagree.

[Anonymous No.9675229]

>>9674308
If this isn't bait you need to go smash textbooks into your face

[Anonymous No.9675231]

>>9675227
this is now a "bad capacitory" thread
https://www.youtube.com/watch?v=AvlNKZ8GzEg

[Anonymous No.9675239]

>>9675231
>capacitory
s/b "capacitor", duh
~ When A Good Capacitor Turns Bad ~
http://www.instructables.com/id/What-is-a-Bad-Capacitor/

[Anonymous No.9675243]

>>9675239
Bad Capacitors
https://www.youtube.com/watch?v=ngA4k32jLGc

[Anonymous No.9675426]

>>9675227
I more meant there's no good or bad in terms of capacitence since the person I responded to was implying a 10pF cap is bad because it is small. I'll grant you I didn't say that explicitly though. Of course a capacitor can be bad like an electrolytic whose electrolyte dried up and has a high ESR or one of those old paper caps from vacuum tube equipment where the paper breaks down and becomes conductive allowing DC to leak through.

[Anonymous No.9675428]

>>9674308
Have you even taken high school physics what the fuck.

[Anonymous No.9675500]

>>9671855
wtf magic is real
electricity confirmed for mana

[Anonymous No.9675804]

>>9675500
Go back to sleep

[Anonymous No.9675808]

>>9675500
A deep deep sleep