Posted: 3/21/2008 12:41:49 PM EDT
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Holy crap. I'm supposed to take the General exam tomorrow but I doubt I'm going to. How the heck do people understand all these formulas and crap? I've read all the I, V, E, and don't understand a thing. 3+.707 square root RMS la la la. My head hurts. |
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Ohm's law is important to understand, not just for ham radio. Here's a page that makes an attempt to explain it using the common water analogy: www.hamuniverse.com/ohmslaw.html I found it also helpful to learn that batteries have a capacity measured in amp hours, or milliamp hours. Thus, a 10 amp hour battery can supply 1 amp for 10 hours, or 10 amps for 1 hour (hypothetically; in practice, there are some other factors at work, but those will be roughly accurate numbers). That is, a 12 volt battery might not store very much power if it has a low amp hour capacity, since it will drain quickly. Think of it as a wide hose fed by a very limited water supply. On the other hand, a 12 volt car battery, with probably at least 100 amp hours capacity, can feed a 10 amp current for at least 10 hours (hypothetically). This helped me understand the relationship between voltage, current, resistance, and power. Note, though, that you don't have to kill yourself over this. If you aren't ready for the test tomorrow, maybe try it anyway, and if you screw up, fine, you're out $12. Work on it some more and try again in a month or two. Rote memorization is a very hard approach to the general test, if you don't already have a solid grasp on electronics. |
Thanks. I understand Ohms law, though I'm not sure when I would ever need it. It's the XL=2Pi f L etc that kills me. I have no idea why I'd ever need to know it and will have to put in quite a bit of studying to figure it out. I'll do it so I can earn my General ticket, but it's going to take some time. I really don't see how it's important to me. I'm not building anything. |
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I took my calculator with me to my general test in case there was a formula question on it. I never even had to open my calculator. Very few questions on the test might require some formula work. The rest of it is mostly common sense, general good amateur practice, and RF safety. Semper Fi |
Well, the whole point of ham radio as opposed to CB, FRS etc. is that you *can* build stuff, or modify stuff and then inflict your creation on people world-wide  For that reason, you are expected to have at least a little bit of knowledge about what you are doing. Where might you use ohms law? Well, lets suppose you are putting a radio in your car. You know how much current it takes when you transmit, so you can look up the resistance per foot of the wire you intend to connect it with, and wok out how much voltage drop there will be when you press the TX key. You may then decide you want thicker wire, or maybe that the super-thick stuff someone is trying to sell you will be a waste of money, and the stuff you have at home will do just fine. The f=1/2Pi(sqroot(LC)) is used to determine resonant frequency. You can use this to build filters to keep interfering signals out of your kit - or more likely out of your TV, phone or HiFi (or that of your neighbors). Anyway - go try the test. If you don't pass, come back here and we can probably help you understand most of this stuff the easy way. |
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Martlet, remember I started studying around March 4, 2008 for my Technician and finished my Extra Yesterday March 20, 2008. Three weeks in all. All I did was go over the practice tests on www.qrz.com. They are the only ones I used, don't worry so much just go over the practice tests and you will be good to go. Like I said before if I can do anyone can. I have to admit that I am not the sharpest pencil in the box and consider myself about as sharp as a bowling ball.  There isn't going to be many of the math or calulation problems. Now go take that General test.  |
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You should be happy that you are no longer required to pass the 5 wpm morse code requirement that was still in effect just 1 year ago. it took me 12 weeks of practice every day just to pass the test and then it took me two tries. The written exam was nothing compred to that.
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One 'trick' a lot of people find successful is to read through the question pool and memorize ONLY THE RIGHT ANSWER. That way, the distractor questions are foreign to you and you won't recognize them. Best of luck! |
That's the only thing I could pass! I had to learn morse in the service. |
Well, I got the book on Wednesday, and spent my spare time actually reading it and trying to understand the concepts. It's impossible for me. I'd actually need someone to pull apart the radio and SHOW me for me to get it, while explaining it in layman's terms. I was supposed to take the test at noon today, and about 9am I started panicking, since I understood nothing. I then spent the next two hours not trying to understand it, but trying to memorize the practice tests. The last 4 practice tests I took I scored in the 80's, as opposed to 50's when I first started taking them. Between memorizing the answers and lucking out with the test questions I drew, I managed to only get one wrong. I'm going to allow myself more study time before taking the Extra. |
Yes, do not study the wrong answers! |
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I took the General exam right after I passed my Tech. (I had no idea you could take the next level up for free!) I got 20 out of 35 right. I didn't pass, but I feel really good about that score, especially since I hadn't even studied for it. At least now I'll prep for General and Extra to kill two birds with one stone, so to speak... |
+1 written was nothing compared to the code. And I haven't even tried to copy any code since I got my General. I just wanted HF phone privileges
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+3.1415 I think it was section 5 with all the formulas. Wow. I know/knew how to do capacitive and inductive reluctance, phase angles, and the ohm's law stuff. Ohm's law I own as well as old Eli the Iceman but I wasn't going to put the horsepower into remembering the reactantance calculations. I leaned the other elements well enough to compensate for my lack of care for the formulas. I passed on the first shot. |
I think you mah have had a bad experience with a science/math teacher at some point in your life. If you had had a good one, not only would this level of stuff seem easy, but it would have been interesting too. If/when you have to time, do come back here and let us know you want to start to get the basics understood and I (and a few others it seems) will gladly help. |
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Use this site to practice HOT LINK. It uses the actual pool questions to generate the tests. This way you can figure out what you know and what you need to work on. Choose/dot "Element 3-2007 - General (effective 1 July 2007)" Then click the "Go to exam" button Choose/dot "Practice examination on the full Element 3-2007" Then click the "Go to exam" button |