What is the DC current value that will give you the same amount of heat as 1.0 amp rms going through a 10 ohm resistor?

A).637 a
b) .707 a
c) 1.0 a
d) 1.41 a



[This message has been edited by Cinner (edited 04-05-2006).]

C--1 ampere

Actually it is (b).707

Roger

I agree with NJ. If you multiply the RMS by .707 again, it becomes PMS, which should be avoided.
Joe

Oooooops, I read the question again

I also agree with NJ

Roger

Shouldn't the answer be:

1/0.707 = 1.41

1.41 x .637 = 0.9 amps.

Do you agree?

Cinner, the "rms" (which I somehow read as "AC" when I first read the question, who knows where my reading skills jaunted off to) already has the AC value equal to the DC value.

Roger

Cinner,
A few years ago, meters started coming out with the "True RMS" labels all over them. These meters give you a reading that is already the peak value X .707, or the RMS, or the heating value. If you had a less spiffy, average reading meter, you would take the displayed "average" value / .637, to get to peak, and then X .707 to get to your RMS value. Hope this helps.
Joe
But still avoid the PMS.

[This message has been edited by JoeTestingEngr (edited 04-05-2006).]

And the 10-ohm figure specified is one of these pieces of data thrown in to a question which is of no significance.

Since P = I^2 x R, 1 amp DC will give the same amount of heat as 1 amp RMS AC no matter what the resistance value (so long as it's the same in both cases, of course).

Answer C, 1 Amp.

what kind of a meter would you use to measure the pms?

A calendar?

LOL

NJ: A calendar?
It is true that a calendar can be used for PMS (Predicting Mean Spouse), but not really as a measurement system. Since PMS still relates to a heating value, consider using infra red measurement from as far away as possible.
Joe

Joe, I would not want to use my infrared camera to measure (Predicting Mean Spouse). I do not think I could get far enough away fast enough.

Al

Once made the mistake of asking my wife about why a calendar was required for Predicting Mean Spouse.


"BECAUSE IT BLOODY WELL IS, THAT'S WHY!!!!!!!!"
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.i'm over here, my little nest of vipers

Careful Capt. Al I have your home phone number.

You can always tell around here. The trades on my wife's jobs are wearing arc flash PPE and everyone has their hard hat on.