Re: There's work, and then there's work

[Bob LaMontagne <rlamont@POSTOFFICE.PROVIDENCE.EDU>]

David Rutherford wrote:

> An analogy might be measuring the amount of water in an elevated tank by
> measuring the water that flows through a hose attached to the tank after
> the valve is opened. Imagine that the hose has a hole in the side of it,
> so that the volume of water flowing out of the hole is exactly equal to
> the volume flowing out the end of the hose. In analogy with the
> capacitor experiment, the water flowing out through the side would
> represent the energy lost to heat dissipation in the calorimeter
> experiment, and the water flowing out the end would represent the
> current in the current experiment.

Not really a good analogy - the galvanometer is in series with the resistor in
the calorimeter. A typical cheap lab galvanometer has an internal resistance of
60 Ohms. The resistor in the calorimeter would have to be around 1200 Ohms or
greater to get a 5 percent or less error due to the galvanometer. Or - follow
Ludwik's suggestion of using an oscilloscope and measure the voltage instead.

Bob at PC