RL Circuit Refresher

[jendrix]

Hi, I have just been refreshing my theory and was going over a parallel RL circuit, like this one.

The site I was reading had this for the total current

I tried some values as a test but it doesn't give me the correct answer, for total current. eg if I set
V=10V
R=2.5ohm
jXl=5ohm

Then I_R=10/2.5 =4A

I_L=10/5=2A

I_T=√4² +2² =4.47A

However when I try the formula from the second answer I get 10/(2.5-2j) which following the maths gives me 2.44+1.95j=3.12A

Am I going wrong somewhere or is it the formula?


Thanks

 

[jim hardy]

However when I try the formula from the second answer I get 10/(2.5-2j) which following the maths gives me 2.44+1.95j=3.12A

Admittances in parallel add. That should be your approach.

A 'Site', you said ? If it's on the internet it must be right, eh ? See my signature.....

see if that works any better.

old jim

 

[jim hardy]

Oops ----- make that it equals Vin X ( 1/R -j1/ωL )

i put my j in wrong place .

 

[Delta2]

Oops ----- make that it equals Vin X ( 1/R -j1/ωL )

i put my j in wrong place .

Seems we can't even trust Old Jim when he posts at the internet with a computer, cause we can never trust a computer with anything important

Ok seriously speaking that was a minor mistake, I didn't notice it either, I just noticed the huge mistake in the algebra in the OP.

 

[jim hardy]

i do that all the time. I'm just clumsy.

Thanks @Delta²

 

[jendrix]

i do that all the time. I'm just clumsy.

Thanks @Delta²

Thanks Jim for clearing that up