Basic Music TheoryIntroduction
The Major Scale
A key signature is the set of sharps or flats necessary to produce the appropriate scale pattern for a given key. The key signature is unique for the type of scale that you are using. That is to say, if you follow the major scale pattern starting on any note, you will get a different set — and a different number — of sharps or flats for each starting note. The key signature, then, defines the key that a composition (or section thereof) is in.
As we saw in the previous lesson, the C major scale has no sharps or flats. The key signature for the key of C, therefore, is no sharps or flats.
In the G major scale, it was necessary to raise the F to an F-sharp to produce the necessary pattern of whole and half steps. So the key signature for G major is F-sharp. In notation, the key signature is placed at the beginning of the line, just after the clef:
The key of D has 2 sharps, F# and C#:
The key of F has one flat:
In notation, the order and placement of the sharps and flats do not change. So, for example, in sharp keys, F-sharp is always listed first, then C-sharp, then G-sharp, D-sharp, A-sharp and E-sharp. For flat keys, B-flat is always listed first, then E-flat, A-flat, D-flat, G-flat, and C-flat.
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