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## Exra Exam E3C09 anwer error?

Jan 23rd 2020, 13:46

#### tenthwave

Joined: Dec 5th 2018, 16:38
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Hi All
I'm studying for the Amateur Extra exam. I'm throwing this forum question into "Propagation" to match the Extra exam classification.

Question E3C09 asks about the relative strength of an X3 solar flare compared to an X2 solar flare. The "official" answer seems to be that an X3 is TWICE as strong as an X2, suggesting that the subscript uses a logarithmic scale. A different answer for that question in the exam is that an X3 is 50% stronger than an X2, suggesting that (within the X-class) the subscript uses a linear scale. I think that the "wrong" answer is actually correct.

From what I read on a number of sites on the internet the correct answer should be that, within the X class, the subscripts are linear.
Normally the subscripts range from 1 to 9 except for the X class which can be extended.

The strongest X class flare to date is an X28 which is 28X as strong as an X1.

All of the practice sites say that an X3 is twice as strong as an X2.

Am I missing something here?... misreading the question?
Jan 24th 2020, 11:33

#### tenthwave

Joined: Dec 5th 2018, 16:38
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Total Posts: 0
I kept reading. Wikimedia is clear and consistent with references. The letter classifications C,M,X are each 10x stronger than the previous letter classification. The letters are a quick way to express the exponent of the measure of total flux of X-rays in the 1 to 8 angstrom wavelength range in W/m^2 as seen by the GOES satellite. The X-class range begins at X1 or 1x10^-4 W/m^2 with the index 1 being the "significand" of the exponential notion. (I had to look that up) The X2 classification is then 2x10^-4 W/m^2. M3 is 3x10^-4 W/m^2, etc. The wiki even specifically answers E3C09 by saying that M3 is 50% stronger than M2. If the X subscript really indicated successive factors of 2 in power then the X28 flare of 2003 would have been 2^27 or 1.3x10^8 times more powerful than an M1 rather than a mere 28 times more powerful. Who keeps track of these errors?
Jan 24th 2020, 13:50

#### W1VT

Super Moderator

Joined: Apr 4th 1998, 00:00
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I checked today with the ARRL VEC and received a response. The answer was changed to (B) in the new question pool.

Even though the question has not been withdrawn nor corrected in the current pool, as the deadline for doing that has passed, most VEC and VE teams will avoid using the question.
Feb 8th 2020, 10:56

#### WD3D

Joined: Mar 1st 2011, 09:28
Total Topics: 0
Total Posts: 0
Instructor for one of my IT classes at Penn State told us that Wikimedia, wikipedia etc are not allowed for the purpose of using a quote for a term paper, because they are an open source type web page that anyone can add to or change and the answers are not always right.. Not saying that they are wrong, just saying that they are not always a reliable source of knowledge..

Glad to see that someone is actually looking at the questions and not just parroting off the answers given to them from a online source. Most new hams today refuses to buy a book and just goes on Eham and takes the exams a bunch of times until they manage to guess enough right answers a couple of times and figures that is good enough.. They don't really learn anything, they just do the bare minimum - pass the exam - to get the license..
Feb 8th 2020, 10:56

#### WD3D

Joined: Mar 1st 2011, 09:28
Total Topics: 0
Total Posts: 0
Instructor for one of my IT classes at Penn State told us that Wikimedia, wikipedia etc are not allowed for the purpose of using a quote for a term paper, because they are an open source type web page that anyone can add to or change and the answers are not always right.. Not saying that they are wrong, just saying that they are not always a reliable source of knowledge..

Glad to see that someone is actually looking at the questions and not just parroting off the answers given to them from a online source. Most new hams today refuses to buy a book and just goes on Eham and takes the exams a bunch of times until they manage to guess enough right answers a couple of times and figures that is good enough.. They don't really learn anything, they just do the bare minimum - pass the exam - to get the license..
Aug 2nd 2021, 13:51

#### AE8W

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
Yes, the wiki sites' contents do change so cannot be quoted reliably. On the other hand, they are one of the easiest places to find references in the footers. Those are good and save plenty of time when just needing that extra bit of validation ... not a deep dive but getting into the topics a little deeper.