Ludwik makes a comment that needs correction:
... <snip> <snip>
I had a vacuum diode in mind (yes, it shows my age). Here
the current at V=0 is essentially zero and the current of 2 mA
is reasonable at 4 volts. Yes, the function is not quadratic, but
it looks like that. Now that I am thinking the I=const*V^(3/2)
comes to mind. Isn't this relation called Richardson's law?
Extrapolating from my hypothetical example, by this law,
one finds I= 63 mA at 40 volts, assuming the law is still
valid. The inserted ac source, in my mind, was a thick wire
coil rotating rapidly in magnetic field. It could have been
something else, for example, the secondary winding of
a transformer, or a complex generator.
Ludwik Kowalski
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To understand is to find a satisfactory causal relation.
To explain is to express that understanding.
To teach is to promote understanding.
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