Simple one: current.

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technogeek

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You have a full wave bridge rectifier taking household voltage(110/120) and sending DC to a resistor. Lets say 100 ohms.

Using a regular DVM, what are the values being measured? In other words, is current RMS? Average? Peak?
 
What's the resistor's power rating? It needs to be rated for at least 288W (assuming you have a large capacitor giving virtually no ripple).

The input current will be drawn in pulses rather than continously.

Use SPICE simulation software to answer your questions.
 
hm mains power ? be careful a beafy resistor may be a beafy resistor no more after that just remember that doubling the voltage quadruples the power and so on so just pull out ur pocket calculator and make sure that roaster ain't gona roast. what are you actually trying to do, also remember in your calculations that with a capacitor it will receive anything up to peak volatage which on 110/120 is something like 150-160 volts (Vrms X 2sqr) so you will have DOUBLE the wattage.
 
As a matter of interest, when I was at college, we were mistakenly sent to the heavy machines lab one class a week - and one of the things we did there was phase shift - using a capacitor and a resistor. The capacitor and resistor were on wheels, probably 3 feet tall, and a foot square! - to power them we used three phase mains (440V) from bare brass, unswitched, screw terminals on the walls!.

After a few weeks of this, when they had us dropping magnets in coils and watching galvanometers go 'wheeeeeeee' I had had enough!. The lecturer came across and said "what are you doing", and I said "I'm not doing this load of old crap, I did this back in the 1st form at secondary school!" - at this point he went a funny colour and stormed out, presumably to have me taken out and hanged!!.

Anyway, the outcome was that it was all a terrible mistake, and they had sent us to the wrong class - yet no one else complained, including those who were in their EIGHTH year there! (day release, not full time), it was my third year!.
 
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