On 28 Feb 2005 13:25:02 -0800, jim rozen
wrote:

In article , Robert Swinney says...

Jim,

Does this mean 1000 pf is the capacitance of two cars very close together
with each forming one plate of a capacitor?

With the earth in between. The implication is that
one car to ground is about 2000 pf. This is within
a factor of two from a simply calculated value, with
10 cm being the separation, and 10 sq M of plate area.

What this says is that at 1 MHz, the car body is coupled
to the ground via an approximately 80 ohm resistor. This
is large enough that there could be significant rf voltages
developed on the exterior of the car body at that frequency.

It implies that Jerry's suggestion (at am frequencies
the whip may be an electrostatic probe to measure the
body voltage) is indeed plausible.

Jim
Jim,
I have found the capacitance between cars to increase with the
distance. In fact, with the cars 6 inches the capacitance is zero.
Unless you use real skinny people. Then the capacitance rises with the
length of the cars.
ERS