The keys that feature only F sharp (F#) in their key signature are G major and its relative minor, E minor.
A key signature displaying only one sharp consistently indicates F-sharp. This specific sharp is characteristic of two related keys: G major and E minor. These keys are known as relative major and minor, meaning they share the same key signature.
Understanding Key Signatures with One Sharp
Key signatures are sets of sharps or flats placed on the staff at the beginning of a piece of music, indicating which notes are to be consistently played higher (sharps) or lower (flats) throughout the piece, unless otherwise marked. When a key signature contains only one sharp, that sharp is always F-sharp.- G Major: This is the major key that naturally includes F# as its seventh scale degree (leading tone). Its scale is G-A-B-C-D-E-F#-G.
- E Minor: This is the relative minor of G major. Its natural minor scale is E-F#-G-A-B-C-D-E, which also contains F#. While different forms of the minor scale exist (harmonic and melodic), the key signature for E minor universally shows one sharp (F#).
Relationship Between G Major and E Minor
G major and E minor are relative keys. This means they share the exact same key signature and contain the same set of notes. The key signature determines the notes that are sharpened or flattened, but the specific tonic (home note) of the piece determines whether it's in the major or minor mode.To distinguish between G major and E minor when seeing a single F# in the key signature, musicians typically look for:
- The starting and ending notes of the melody.
- The presence of the leading tone (D# in E harmonic minor) or specific melodic patterns that define the minor mode.
- The overall harmonic progression and resolution points within the composition.
Key Signature Overview: One Sharp
| Key Name | Mode | Notes in Key (excluding accidentals) | Sharps in Key Signature | Relative Key |
|---|---|---|---|---|
| G Major | Major | G, A, B, C, D, E, F# | F# | E Minor |
| E Minor | Minor | E, F#, G, A, B, C, D | F# | G Major |
Understanding key signatures is fundamental to music theory and performance, providing a quick visual reference for the tonal center of a composition. For more details on key signatures, you can refer to resources on music theory fundamentals.
