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Author Topic: Passing rate per exam session: 3 out of 8?  (Read 41035 times)
KJ6ZOL
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Posts: 820




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« on: June 15, 2015, 11:30:37 PM »

So just out of curiosity, I punched "KJ6ZO" into the ULS search function to see how many licenses were issued in my Tech exam session, which was 9/1/12 (made final on 9/7). To my shock there was only THREE! I remember there being around 7 or 8, maybe 9, people in the session. I upgraded to General a month later at a different exam session. One guy got a vanity call when he became an Extra in the spring of 2013, one is still a Tech, and me. Are there still exam sessions with a pass rate of 33%? Study, it's not THAT hard!  Roll Eyes Roll Eyes
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K8PRG
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« Reply #1 on: June 16, 2015, 04:19:30 AM »

Who are you posting this for?? If they didn't get their licence, I doubt they spend much time on this forum.
But OK, I'll play.....It's not THAT easy...studying for me never was, still isn't. Especially on subject matter that I know nothing about, and for the most part, find down right boring.
I managed to pass General this past week-end, but I spent two months "studying", that is, memorizing the correct answers to the study guide questions.
Just never ask me "What is the RMS voltage across a 500-turn secondary winding in a transformer if the 2250-turn primary is connected to 120 VAC?" because I won't know.
It's easy for someone to say how "easy" something is, once they've done it. But I feel for the guys who have not passed the tests, as bad as they wanted to, just to hear someone say how easy it is.


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KG6AF
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Posts: 473




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« Reply #2 on: June 16, 2015, 08:58:23 AM »

In our VE sessions, I'd estimate that 80 to 90 percent of Technician candidates pass.  Of course, this is Silicon Valley, and that may skew things a bit.

My general rule of thumb is, people who study for a test have an excellent chance of passing. Those who don't study (say, people who just passed the Tech and take the General on a whim) seldom do, the notable exception being those with an engineering or science background.

Not that anyone should feel bad about having to take a test multiple times.  As we point out to test takers, no one is going to publish their score online, or the number of times they took the test.
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N2EY
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« Reply #3 on: June 16, 2015, 10:46:03 AM »

"What is the RMS voltage across a 500-turn secondary winding in a transformer if the 2250-turn primary is connected to 120 VAC?"

That's easy!

2250 turns divided by 120 volts is 18.75 turns/volt.

500 turns divided by 18.75 turns/volt is 26.67 volts.

----

That said, consider the following:

When someone goes to a VE session, the fee paid usually entitles them to 1 try at each of the tests they have not passed yet.

Many of us encourage folks to try every test - they are at the session anyway, they paid the fee, what can it hurt to try?

So, someone goes to a VE session for the Tech, passes it, tries the General, passes it, tries the Extra and fails. Or some variation of that.

The result is an apparent low pass rate, but in reality, it's not as bad as it seems.

73 de Jim, N2EY
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WA2ISE
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« Reply #4 on: June 16, 2015, 01:02:05 PM »

"What is the RMS voltage across a 500-turn secondary winding in a transformer if the 2250-turn primary is connected to 120 VAC?"

That's easy!

2250 turns divided by 120 volts is 18.75 turns/volt.

500 turns divided by 18.75 turns/volt is 26.67 volts.
----

It's 120/2250 = 0.053 volts/turn Then take that and multiply by 500 turns = 26.67V

You had it upsidedown twice, and both errors cancelled out, so you got the right answer.   Grin

Anyway, to estimate the number of turns you need to operate a transformer, figure out the cross section area of the transformer core (in the plane that taken by a turn of wire around that core) in square inches, and take that number and divide 800 with it.  800/area=(turns for the 120V 60Hz primary). A bigger core makes for fewer turns. The reason for the 800 is that we need to keep the magnetic flux low enough to avoid saturating the transformer core.  If saturation happens, then the core will act like it's no longer there, and the primary inductance will drop very low, and then it will draw way more inductive current off the power line.  Which will make for really hot wire, not good.  The main reason you can't take a 120V to 12V transformer and feed 120V into the 12V secondary and expect to see 1200V out of the old primary.  You'll set it on fire... For a transformer that needs 2250 turns the core would be tiny, like 0.35 square inches.  

I was living in Silicon Valley when I took the tests to upgrade from Tech Plus to Extra (In Y2K, you'd take the advanced and extra writtens, and then cash in the CSCEs when the new rules kicked in that year).  The VEC told me I did really well on the tests, missing one or two questions.    Better than when I first got licensed, I barely passed the written...
« Last Edit: June 16, 2015, 01:05:44 PM by WA2ISE » Logged
WS3N
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Posts: 1258




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« Reply #5 on: June 16, 2015, 06:02:51 PM »

"What is the RMS voltage across a 500-turn secondary winding in a transformer if the 2250-turn primary is connected to 120 VAC?"

That's easy!

2250 turns divided by 120 volts is 18.75 turns/volt.

500 turns divided by 18.75 turns/volt is 26.67 volts.
----

It's 120/2250 = 0.053 volts/turn Then take that and multiply by 500 turns = 26.67V

You had it upsidedown twice, and both errors cancelled out, so you got the right answer.   Grin

The ratio of the voltages equals the ratio of the turns,

v2/v1 = n2/n1.


You say v2 = (v1/n1) n2,

he says v2 = n2/(n1/v1).

His expression is completely equivalent to yours. There are no errors, it's just not the way you memorized it. He simply chose to express the relationship in terms of a reciprocal ("upsidedown").
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KB1WSY
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Posts: 1282




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« Reply #6 on: June 19, 2015, 05:39:29 AM »

His expression is completely equivalent to yours. There are no errors, it's just not the way you memorized it. He simply chose to express the relationship in terms of a reciprocal ("upsidedown").

You can do it a third way:

500 / 2250 * 120 = 26.67

or V2 = n1/n2 * V1

If you understand the fundamental principle, you can devise your own equation without having to memorize anything. They are all the same, it's just a question of rearranging the terms.

73 de Martin, KB1WSY
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WS3N
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Posts: 1258




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« Reply #7 on: June 19, 2015, 10:48:19 AM »

or V2 = n1/n2 * V1

Not quite.

v2/v1 = n2/n1

or

v2 = (n2/n1) v1


If you understand the fundamental principle, you can devise your own equation without having to memorize anything. They are all the same, it's just a question of rearranging the terms.

Yes, it's ridiculous to make distinctions between such trivial rearrangements.
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K7KBN
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Posts: 3473




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« Reply #8 on: June 22, 2015, 04:27:59 PM »

E = IR
E = MC²

therefore IR = MC².
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73
Pat K7KBN
CWO4 USNR Ret.
K6BBB
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Posts: 0




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« Reply #9 on: June 23, 2015, 02:34:18 PM »

E = IR
E = MC²

therefore IR = MC².

 Cheesy Cheesy
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G3RZP
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Posts: 8123




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« Reply #10 on: June 28, 2015, 10:44:53 AM »

Quote
E = IR
E = MC²

therefore IR = MC²

Only if apples are potatoes AND pigs are eagles
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K6CPO
Member

Posts: 398




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« Reply #11 on: June 29, 2015, 11:19:34 AM »

We held a testing session Field Day morning.  We had nine candidates show up to take various examinations.  They took a total of fifteen examinations and at the end we had two new Technicians, three upgrades to General, and one individual who took all three and went from not licensed to Extra.  Three candidates attempted the upgrade to General and failed. 

I think that's a pretty good pass percentage.  The three general candidates that failed were trying to upgrade before the next question pool goes into effect and all were unprepared.  Two are in my club and I expect they will pass in the near future.
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W6RZ
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Posts: 160




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« Reply #12 on: June 30, 2015, 12:37:45 AM »

Here's the tally from last year's DEFCON.

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