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Re: [Phys-l] CFLs again



Since the CFLs use a transformer, (and possible a capacitor input) the i-V phase may not be zero (impedance not pure R) and therefore, i*V may not = W.

That's why I asked. The old d-Arsonval watt meters automatically corrected for this by using the i to power (w/ a shunt) the electro-magnet and the V w/ a multiplier the moving coil. To check this use a double beam or dual channel CRO. One channel; reads the i using a small value resistor in series and the other the V across the lamp. Are they in phase? One may thereby measure the angle and correct the i*V value.

bc, owner of two d-Arsonval watt meters.

Spagna Jr., George wrote:

Bernard asks:


-----Original Message-----
From: phys-l-bounces@carnot.physics.buffalo.edu

[mailto:phys-l->bounces@carnot.physics.buffalo.edu] On Behalf Of Bernard
Cleyet


bc wishes to know the method GSJ used to measure power.


Students put an ammeter in series with the lamp, and voltmeter in
parallel. Both were digital multimeters reading true RMS current and
voltage. P = IV


cut