Re: Ohm's Law

[Bob Sciamanda <trebor@VELOCITY.NET>]

1) Pre-fogging a photographic film for increased linearity/sensitivity to
small optical signal variations.
2) Biasing almost any sensor in the same way: a scale, an accelerometer.
3) Any standard deviation is defined as a variation from the ("DC bias")
mean value.

IE.,  Zero is not always the most useful base value for measurements
(comparisons).

Bob

Bob Sciamanda (W3NLV)
Physics, Edinboro Univ of PA (em)
trebor@velocity.net
http://www.velocity.net/~trebor

----- Original Message -----
From: Ludwik Kowalski <KowalskiL@MAIL.MONTCLAIR.EDU>
To: <PHYS-L@lists.nau.edu>
Sent: Monday, November 08, 1999 11:48 AM
Subject: Re: Ohm's Law


> Consider a diode whose I=f(V) looks like y=x^2 between V=0 and
> V=6 volts. You apply 4 V and the current of 2 mA is flowing. You
> say R=2000 ohms. This is a dc circuit. Add an ac source in series.
> Assume its inner resistance is negligible and the dop amplitude
> is 1 volt. The alternating current is superimposed on the dc. Divide
> your 1 volt by the amplitude of the current and you have the dynamic
> resistance. It is smaller than 2000 ohms. That is how I see it. The ac
> and the dc encounter different resistances.
>
> What would be a good mechanical or optical analogy for this?
> Ludwik Kowalski