On Fri, Nov 28, 2008 at 01:10:32PM -0600, lee wrote:
On Fri, Nov 28, 2008 at 06:59:06PM +0000, Tzafrir Cohen wrote:
A voltmeter has two connectors and shows the potential differences
between them.
This is unlike an Ampermeter that shows the current flowing through it.
If you have a multimeter that can measure voltage or current, both
modes are basically the same. The difference is only in where most of
the current flows.
They're the same internally in that even in current mode the meter is
measuring a voltage (the voltage drop between the meter's terminals,
a known but very small-valued resistor), but they're quite different,
basically.
Is it even possible to measure a mere potential?
Back to a water analogy, consider you're holding a bucket of water.
The height of the surface of the water above the floor represents its
potential for doing work, its energy.
No flow is required to know that value, the height. You can increase
or decrease it just by raising or lowering the bucket. The height is
not affected by the depth of the water, the surface area of the water,
the volume of the water -- it's not even a property of the water, but
rather of its relationship to the floor. If you're standing on stairs,
the water has a different height relative to each stair.
Etc.