Originally Posted by: equatorHey Jolly, I think you missed the part when I said...
So here is the A major Scale:
[A-B-C#-D-E-F#-G#]
In relation to the root, "C#" is a Major 3rd, and what happens when you flat a major interval?...you get a minor interval. So if you flat the "C#" you get a C natural, which now is minor 3rd.
Now "B" is the major 2nd, right? and what happens when you sharp a major interval?...you get an augmented, so raise the "B" half step, and you have a "C". Thus, A-C is an augmented 2nd.
That is why I stated:
*[1-b3]=A-C
*[1-#2]=A-C
Both result in the same notes(A & C).
But the first is a Minor 3rd interval.
The second is an Augmented 2nd.

I see where you got confused. That example is not in the key of C.
It is in the key of A major.

If you raise the B to a C you get a minor third, if you raise the B to a B# you get an augmented second. I know what key it's in, I'm not saying it's in the key of C, I'm saying A to C is a minor third, not an augmented second. I know they have the same intervallic value, but you'd have to label that C a B# in order for it to be an augmented second. As it is it's a minor third. See, if you go from A to C, you have to pass through the B, which would make it some form of third. A-B-C#-D-E-F#-G#-A, the augmented second would be a B#, not a C, understand? I know they're enharmonic notes, but technically it's wrong to call A to C an augmented second, that's all I was correcting. See, when you raise that B a half step, if you want it to be an augmented second, you have to call it a B#. If you call it a C it's a minor third. I'm not quite sure why you think I read it as the key of C... Even if I DID read it as such, the interval A-C is still a minor third, not an augmented second.

See, the part where you make a mistake here is where you say "raise the B a half step and you get C." That's true, but if you want an augmented second, you replace that C with the enharmonic B#. Understand? An augmented second from A is not C and if I put that on my music theory exam, my professor would eat my face.