General > General Technical Chat
Veritasium "How Electricity Actually Works"
electrodacus:
--- Quote from: dunkemhigh on May 16, 2022, 01:13:42 am ---
--- Quote ---It is a distributed capacitance and there is inductance involved so charging of each capacitor (seens a series of lumped components) will be delayed.
--- End quote ---
Doesn't matter if it's distributed - the entire thing has a very very short time constant. All you're saying is that if you imagine it comprised 100 smaller capacitors, each will be 2.1ff (i.e. 2.1pf/100).
And... if there's a 18V pulse going in, how come there's only 5V coming out the other side?
--- End quote ---
You are looking at the capacitance of a single conductor. The way that Derek's experiment is setup the capacity is between two wires with 1m distance between them and 10m long in each direction.
So total capacitance will be around 42pf for the two 10m long parallel copper pipes and I have that split in to 100 so 0.42pf for each element.
Voltage on the resistor is proportional with the current passing through the resistor while this distributed capacitance charges so it forms a divider with the line impedance. And there are two lines on each side of the resistor.
hamster_nz:
--- Quote from: dunkemhigh on May 16, 2022, 01:13:42 am ---
--- Quote ---It is a distributed capacitance and there is inductance involved so charging of each capacitor (seens a series of lumped components) will be delayed.
--- End quote ---
Doesn't matter if it's distributed - the entire thing has a very very short time constant. All you're saying is that if you imagine it comprised 100 smaller capacitors, each will be 2.1ff (i.e. 2.1pf/100).
And... if there's a 18V pulse going in, how come there's only 5V coming out the other side?
--- End quote ---
Just for fun I divided capacitors like this, and the prompts thoughts that energy is stored in the dielectric between the plates. >:D
SiliconWizard:
Is the electric field really between the plates?
electrodacus:
--- Quote from: SiliconWizard on May 16, 2022, 01:59:40 am ---Is the electric field really between the plates?
--- End quote ---
For a capacitor yes. The plates have large surface area and distance between plates is super small in comparison thus field lines are all between the plates.
With wires separated by 1m of air it still between the wires but a bit more "loose" if this is the correct word.
electrodacus:
--- Quote from: dunkemhigh on May 16, 2022, 01:13:42 am ---
Doesn't matter if it's distributed - the entire thing has a very very short time constant. All you're saying is that if you imagine it comprised 100 smaller capacitors, each will be 2.1ff (i.e. 2.1pf/100).
--- End quote ---
Ues this calculator https://www.emisoftware.com/calculator/wire-pair-capacitance/
You can use 12mm wire radius 1m separation and 10m length and you will get 62pF total
I also checked with 1mm radius for fire and got about 40pf so I used 42pf in my simulation just to be conservative.
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