The other day, I got a phone call from a former student. He was a bit perturbed because he’d started studying for the Extra Class exam, and right off the bat, he found himself in some deep water.
The first topic that I cover is resonance. I jump right in and define resonant frequency as the frequency at which inductive reactance of a circuit equals the capacitive reactance of a circuit. That is when 2πfL=1/(2πfC), and if you do the math, the resonant frequency, fr = 1/(2π√(LC).
Now, I’m going to take some of the blame for my friend’s predicament. The reason for this is that I really didn’t review the idea of reactance. I just assumed that they’d recall this from the General Class material. When I explained this over the phone, he got it, but I can see where my study guide could be a little confusing.
After the little lesson, we talked some more about the Extra Class exam, and I could tell that he’d been looking ahead and getting a little overwhelmed. I then suggested that instead of getting anxious about all of the material yet to come, that he take it a little at a time. Take a handful of questions and do a little Googling. As far as understanding LC circuits, I suggested that he look at a a couple of my previous blog posts:
- https://www.kb6nu.com/reader-writes-help-rlc-circuits/
- https://www.kb6nu.com/videos-lc-circuits-oscillate/
There is a lot of material covered by the Extra Class exam. That’s just the nature of the beast. Passing the Extra Class exam is supposed to mean that you’ve achieved a certain level of expertise. If you take it a little at a time, though, and don’t try to cram it all in at once, you’ll make learning all that material more manageable.
As far as my study guide goes, I now see how I can improve it. This is why reader feedback is so important. If you’re having trouble with a particular topic on any of the tests, please contact me. I’d be happy to help you personally, and by doing so, you’ll be helping me become a better teacher and helping me improve my study guides.
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