5.10 Relative minor and relative major
Because the scales of C major and A minor have the same key signature, they are clearly related. Indeed, the key of A minor is called the relative minor of C major. Conversely, C major is called the relative major of A minor. If we look at the relationship between C and A on a keyboard in Example 54, we can count the number of semitones between them (it’s quicker to do this counting from C down to A rather than C up to the higher A). The result is three – C–B, B–B♭, B♭–A. So the relative minor of a major key, and the minor key that has the same key signature, is three semitones lower than its major counterpart.
By following this principle, we can work out the relative minor key of G major, the second major key we examined in Section 5.3. Look at Example 54 again. Three semitones down from G, namely: G–F♯, F♯–F and F–E is E. E minor is thus the relative minor of G major and has the same key signature, one sharp.
If we now follow the intervallic patterns we discovered in the various forms of the minor scale – the pattern of the natural form was T S T T S T T, for instance – we can generate the three forms of the E minor scale shown in Example 55. Fundamentally, we have only one different note from those we had in the scale of A minor, the F♯. However, with the three different forms (natural, harmonic and melodic) the same question arises with regards to the sixth and seventh notes up the scale – should one or both be sharpened or not?
You can find a summary chart of the minor scales with up to four-sharp and four-flat key signatures in Example 56. Study this carefully – minor scales, especially those with three or four flats or sharps, are more difficult to grasp than their relative-major counterparts. So take time over this.
The following two activities assess your knowledge of minor key signatures of up to four flats and four sharps, and of the minor scales that have these key signatures. Try them now.