inductor question

[Stig]

why uni-henries and mili-henries?

Example:

245 uH

.245 mH

Are these the same value?

Thanks,

Stig

[djk]

.040mH and 40µH are the same value.Decimal points don't always reproduce well.European standards omit decimal points.A 2.7 ohm resistor would be 2R7 and a 2,700 ohm would be 2K7.They would say fourty micro-Henries rather than point oh four oh milli-Henries.

[WMcD]

A milli is 1/1,000 and the m is used. It is 10E-3 by some notation. So you have milli-henries.

A micro is 1/1,000,000 and the u is often used as a substitute for the Greek mu. That letter has a little decender hanging down from the leftmost edge. It is 10E-6. You have micro-henries.

This system is also used with capacitors. The most common unit is the microfarad. That is 10E-6 farads or 1/1,000,000. 1,000 uF would be a millifarad, but I've not see that used.

Oh. A pico-farad is 1/1,000,000,000. You see notations to pF.

Resistors have large values and another system is used (Latin?). 1,000 ohms is a kilo-ohm. 1,000,000 ohms is a mega-ohm.

Please note the system is used in other areas of science. A milliliter is 1/1000 of a liter. It also happens to be a cubic centimeter. That is a cube 1/100 meters on a side.

See, it all makes sense once you know the language.

You'll note that values are multiples of 1,000. That is called "engineering notation". You will see that as a choice of formats on some calculators.

Gil

[Stig]

Just wanted to say a late thanks to djk and William F. Gil McDermott for your answers to my question.

I've been busy for a while...

Thanks again,

Stig