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Re: [Phys-l] glassware needed

On Jan 1, 2009, at 5:29 PM, chuck britton wrote:

Make sure that the 'inexpensive' watt-meter can correctly handle non-
sinusoidal wave forms.
Triac's don't output sine wave by a LONG shot.

True RMS measurement are often NOT produced by cheap meters.

That is why I would use a d.c. power supply (measuring I and U and calculating the input energy as U*I*t).

One of the "excess heat" claims was recently withdrawn (by two cold fusion researchers) because of the systematic wattmeter errors. The electric current (in a high voltage electrolytic cell) was fluctuating rapidly and inexpensive instruments were not able to handle this properly.

Ludwik Kowalski, a retired physics teacher
5 Horizon Road, Apt. 2702, Fort Lee, NJ, 07024, USA
Also an amateur journalist at