A 100 mH inductor is placed in parallel with a 100 Ω resistor in a circuit. The circuit has a source voltage of 30 VAC and a frequency of 200 Hz. What is the current through the inductor (rounded)?
Anytime there are components in parallel driven by an ideal voltage source, the current flowing through each component may be calculated independently, as though none of the other components were present.What is the current through the inductor (rounded)?
Hi,Impedance of inductor is sL=jwL.
w=2*pi*f=2*pi*(200 Hz)=1256.64 rad/s
Zl=jwL=j*1256.64*(0.1 H)=125.66j Ohm (this means that your inductor just became a resistor)
Since Zl, a resistor, is in parallel with a 100 Ohm resistor, you have a current divider. Do you know how to find currents in the current divider?
A little off topic.
It has been my experience that reactance is very useless thing. If your instructors require you to find reactance, then go and find it. If they don't ask you to find reactance, then don't waste your time on finding this stupid **** [word blanked out].
There are some fundamental concepts that, if you understand them, make this problem much simpler.A 100 mH inductor is placed in parallel with a 100 Ω resistor in a circuit. The circuit has a source voltage of 30 VAC and a frequency of 200 Hz. What is the current through the inductor (rounded)?
WBahn brings up good point.Hi,
This is a current divider yes, but no reason to bring that up because the voltage will drive the current through the inductor without any influence by the resistor because there is no source impedance.
Therefore the current through the inductor is caused by the voltage only and so can be treated as a reactance: iL=Vs/xL
and also: iR=Vs/R
Also, is language like that allowed on this forum? No need for that though even if it is, right?
Hi,Here is what I did. unfortunately it does not match the answers that were given. so what did i do wrong?
Hi,WBahn brings up good point.
If OP is asked to find full value of the current, magnitude and phase, then reactance is useless because it only gives you magnitude.
Frankly, I do math using complex numbers on my calculator, then tell the calculator to produce magnitude or phase or both, as needed, and once again I don't bother with reactance since the complex value contains everything I might need.
If the point of the exercise to find total current, then:Here is what I did. unfortunately it does not match the answers that were given. so what did i do wrong?
Well... Il is 0.239 A @-90°.As stated in the OP, the question is ONLY asking for the current through the inductor.
What were the answers that were given? We are not mind readers.Here is what I did. unfortunately it does not match the answers that were given. so what did i do wrong?
by Luke James
by Robert Keim