# AC Inductor Help

Discussion in 'Homework Help' started by chris3spice, Sep 30, 2012.

1. ### chris3spice Thread Starter New Member

Aug 28, 2012
5
0
Should be simple for some of you guys but I am stuck on it

I have a simple AC Source and an Inductor all that was given me was
Vt = 30 Vrms
It = 15 mA
f = 159.155 kHz

They want me to find L and Xl but when I try to plug the numbers into the formula's I know it doesn't work out so I may be doing it wrong or something so I'd like to know how you'd find it for sure.

I tried dividing I by V to get Xl be cause the book says I=V/Xl

so Xl = .015/30 = .5mH

but when I plug .5mH back in it doesn't work out 30/.0005 = 60000

2. ### Kermit2 AAC Fanatic!

Feb 5, 2010
4,166
1,125
I divided by V = 1/XI not XI

and 1/.0005 is 2000

30/2000 = .015

3. ### chris3spice Thread Starter New Member

Aug 28, 2012
5
0
Thanks! I messed up my algebra...I feel really stupid at the moment now

4. ### vk6zgo Active Member

Jul 21, 2012
677
85
Well for a start Xl is in Ohms not mH!

Xl=V/I,so as you said in your last posting,Xl = 30/.015 =2000Ω!!!!

Xl =2∏fL,where you know what 2∏ is,& f is given:

Dividing Both Sides by 2∏f gives us L=Xl/2∏f (in Henries!)

Last edited: Oct 1, 2012
5. ### vk6zgo Active Member

Jul 21, 2012
677
85
I think a little revision of Ohm's Law may be in order!