Accidentals (Sharps & Flats) can be placed in a Key Signature. Let's see how to use Key Signatures with our Major Scales.
Using Key Signatures
These are the seven major scales we've done so far. C, F, G, D, Eb, C#, Cb. When we put these Major scales together, whenever a flat or sharp was, needed we place it to the left of the note on the same line or space the note uses. Instead of writing sharps and flats every time they occur, they can be placed in what's known as a key signature.
Let's add key signatures to the seven Major scales we've made so far.
C Major Key Signature
We already know the C Major scale has no sharps or flats, so the key signature for C Major doesn't have any either. No sharps and no flats equal the key of C.
F Major Key Signature
The F Major scale has one flat, Bb. The key signature for the F Major scale also has one flat. The flat is placed on the line where the note B is placed. Being in the key signature, it affects every B. So we no longer need to add a flat in front of B to make it Bb. Since the flat for B is now in the key signature, all B's are to be played as Bb.
G Major Key Signature
The G Major scale has one sharp, F#. The key signature for the G Major scale also has one sharp. Here the sharp is placed on the line where the note F is placed. Now that F sharp is placed in the key signature, it affects every F. All F's are to be played as F#'s.
D Major Key Signature
The D Major scale has two sharps, F# and C#. When these are placed in the key signature, every F is played as F# and every C is played as C#. Notice the sharp for F is placed on the line where the note F is placed, and the sharp for C is placed on the space where the note C is placed.
Eb Major Key Signature
The Eb Major scale has three flats, Bb, Eb and Ab. When these flats are placed in the key signature, every B, E, and A are to be played as flat. Bb, Eb and Ab.
C# Major & Cb Major Key Signatures
The maximum number of sharps and flats that can be placed in a key signature are seven. When we looked at the C# Major scale, we saw every note had a sharp. When we looked at the Cb Major scale, we saw every note had a flat. With the sharps and flats moved into the key signature, we still have seven sharps for C# Major and seven flats for Cb Major. With seven sharps, every note is played as a sharp. With seven flats, every note is played as a flat.