# Current question

Hi All...

So, if I have a chip that uses .65 micro amp (.65 uA) and another that uses 100 nA, which is using less power? I don't know what an "nA" is...

Thanks...

100 nA = .1 uA

Oh, a HUGE difference then, thank you!

If you're interested it would be a good idea to read up on SI prefixes:

Specifically you said you don't know what "nA" stands for; it means nanoampere(s).

One "nano-amp" is one billionth of an ampere, or, as retrolefty said, one thousandth of a "micro-amp".

The commonly used prefixes differ by a factor of a thousand…

1G = 1,000,000,000 (giga) - rarely seen in electronics
1M = 1,000,000 (mega)
1k = 1,000 (kilo)

1m = 0.001 (milli)
1u = 0.000001 (micro - the correct symbol is a greek letter mu but my keyboard doesn’t have that!)
1n = 0.000000001 (nano)
1p = 0.000000000001 (pico)

For historical reasons (which annoy me) capacitance values that naturally fall in the nano range are often given in micro or pico range:

47,000pF (more naturally expressed as 47nF)
0.001uF (much more sensible to say 1nF)

This reluctance for the electronics industry to use nano prefix is probably why you aren’t confident about it. Oddly the same thing does not happen with inductance values where nH are routinely used.

1G = 1 000 000 000 (giga) - rarely seen in electronics

Unless you work with RF. Or processor clocks. Or (in my case) both.

For historical reasons (which annoy me) capacitance values that naturally fall in the nano range are often given in micro or pico range:

47,000pF (more naturally expressed as 47nF) 0.001uF (much more sensible to say 1nF)

This reluctance for the electronics industry to use nano prefix is probably why you aren't confident about it. Oddly the same thing does not happen with inductance values where nH are routinely used.

+1 on the annoyance. it also leads to confusion about pf because the uninitiated may think "oh, well - they must meant .001uf"

skyjumper: if I have a chip that uses .65 micro amp (.65 uA) and another that uses 100 nA, which is using less power?

Are they at the same voltage? Power is determined by Voltage and Current, not just one alone.

nF is a new fanged way of indicating a value. Twenty years ago no one used it, mainly because it was an odd power. That is the jump from Farads to micro Farads, ( ten to the minus six) is the same size as the jump to pico farads (ten to the minus 12). It was not used in inductors mainly because values in the nH were not used as electronics didn't go up to those sorts of frequencies. But as you say history annoys you, why were we all so stupid in those days? It must be great being clever.

(If you are from the U.S. then please look up the meaning of irony)

(If you are from the U.S. then please look up the meaning of irony)

Sorry no time, I'm busy trying to program an arduino to change my auto speedometer to read out in furlongs per fortnight.

Lefty

Huh. How recent is the whole "engineering notation" that uses multiples of three for the exponent in scientific notation? I mean, when I learned about the metric system, we learned about all sorts of prefixes (deca, hecto, deci, centi) that are now rarely used. But the bigger prefixs (nano, giga, terra, peta, etc) were rarely used then, perhaps because it wasn't common for measured things to be that big or small (with perhaps the single exception of picoFarads, which were sometimes micro-micro-Farads, but those were only for electronics/physics geeks.)

we learned about all sorts of prefixes (deca, hecto, deci, centi) that are now rarely used.

And then, of course, there's the entomologists. "Millipedes"? "Centipedes"? Utter tosh. They are, surely, kilopedes and hectopedes respectively.

I mean, when I learned about the metric system, we learned about all sorts of prefixes (deca, hecto, deci, centi) that are now rarely used.

They still are. I keep seeing those on my daughter's homework, and I want to scream (mostly because I don't remember them).

There is that centi-meter thingy, though.

(If you are from the U.S. then please look up the meaning of irony)

containing iron?

-j

I think things like "hect-" only really come into use for square measure, like "hectare", which is an area of 10 000 square metres. The are is (the are are?) 100 square metres, or ten metres by ten metres. Using third powers of ten would make for peculiar measurements, i.e., a kiloare would be 100 000 metres square, and would be 316.227 metres on a side.

There's decibels of course and decilitres are sometimes used, but otherwise only centi has survived (centimetre, centilitre) in the real world. Hectare is the unit to all intents and purposes, no-one uses ares do they? Angstroms are gradually losing the battle to nanometres.

And then there's all the informal units http://en.wikipedia.org/wiki/List_of_unusual_units_of_measurement :)

There's decibels of course and decilitres are sometimes used, but otherwise only centi has survived (centimetre, centilitre) in the real world. Hectare is the unit to all intents and purposes, no-one uses ares do they? Angstroms are gradually losing the battle to nanometres.

Decilitres, decagrams, hectograms etc. are all heavily used throughout mainland Europe. I'm not sure that part of the world is part of your real world though.

Never ever seen decagrams or hectograms in UK, nor on any food packaging around Europe - I think this is probably very culturally specific.

Decilitres, decagrams, hectograms etc. are all heavily used throughout mainland Europe.

Really? Like MarkT, I'm mostly basing my experiences on food products. For example at http://sverigeonline.se/ we see thing in packages of "300 g", "1,4 l", etc... I wouldn't entirely trust what is written on packages exported to the US, but that's an actual Swedish website, right?

Am I the only one around here old enough to remember the REAL units for small capacitances - miki-mikes. Hint: Think micro - micro ...

RonR:
Am I the only one around here old enough to remember the REAL units for small capacitances - miki-mikes. Hint: Think micro - micro …

I’m old and uf and uuf was what I grew up with. I don’t mind the new capacitor units so much as how sparsely they label the values on them small ones, 103, how the hell am I suppose to know what units that is? Oh well won’t be a problem for long as soon only fly spec size SMD caps will be avalible and they are to small to try and label.

Lefty