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Fun Electrical Trivia Question

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steveB

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If you want to have fun with your coworkers at coffee break or lunchtime, shout out this trivia question and see who can answer. If you are brave, offer 20 dollars to the person that can get all three parts fully correct.

Part 1: What is the inverse of resistance, and what units are used for it.

Most electrical people will get this one right and say "conductance" with units of either "Siemens" or "mhos". Note that if they say mhos instead of Siemens, they will have a slight advantage on parts 2 and 3.

Part 2: What is the inverse of inductance, and what units are used for it.

Far fewer people will know this, but many will guess reluctance thinking back to their magnetic theory. They will be correct for the term, but they will be incorrect because magnetic reluctance is not the same thing as reluctance as the inverse of inductance. But, give them credit for the correct term. However, if they give the units for magnetic reluctance, and don't say "yrnehs" for the units, they are wrong. Note, that yrneh is Henry spelled backwards, similar to how mho is Ohm spelled backward.

Assuming, someone is smart enough or lucky enough to get part 2 correct, go on to part 3.

Part 3: What is the inverse of capacitance, and what units are used for it.

Only the very sharpest person will get the correct answer of "elastance" with units of darafs (Farad spelled backwards).

If anyone of your coworkers gets all three parts correct, hand over the 20 dollars with a smile on your face, and then bow to that person in the future whenever you see them. :)
 
Interesting. Siemen is SI. Are the others SI?

How do you pronounce "yrneh?" My guess is that the y takes the sound of a vowel. First guess, "erna;" second guess "arna."

BTW, I didn't earn the Jackson. Only got both Mho and Siemen.

John
 
I wouldn't have gotten it right either, and I have no idea how to pronounce "yrneh".

I think the units are SI only in the sense that mho=1/Ohm, yrneh=1/Henry and daraf=1/Farad
 
Hi,

Yes, interesting.

The inverse of inductance is also known as "reciprocal inductance", and the inverse of capacitance is also known as "reciprocal capacitance".

A common symbol for reciprocal capacitance (or elastance) is "S".
But the symbol for reciprocal inductance is more interesting. The symbol for inductance is of course "L", but a common symbol for reciprocal inductance is the capital Gamma, which looks like an upside down "L" :)
The units are also known as reciprocal Farad and reciprocal Henry.

I find that people also have trouble with composite units that sound strange together such as:
feet/foot (feet per foot)
inches/foot (inches per foot)
inches/inch (inches per inch)
etc.
but not too much trouble with feet/second/second.

The names (and units perhaps) for motion derivatives above the second are also interesting if you ever feel like looking them up. They actually have physical significance too.
 
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