If there is a sharp or flat in one half of a piano staff is that sharp/flat continued to the other half of the staff? For example, say there is a C♯ in the left-hand part of the staff, do you implement that sharp on all the Cs regardless of the hand used to play the note? In other words, do you use that same sharp or flat in the treble clef too, if it was marked in the bass clef for another note?
Short answer: Yes-ish.
In your case, Piano music is written with a Grand Staff, binding together a Treble Clef (right hand) and a Bass Clef (left hand), which are seen and played together as if they were one measure and one staff. However, when it comes to notating Accidentals, staves are typically treated independently.
Accidentals apply only for the duration of the measure where they appear, and, oddly, only within the same octave. The exception is when Accidentals are tied across measure lines, in which case, you hold the Accidental tone through the end of the tie.
So, in piano music, although an Accidental indicated in a measure of the Bass Clef is "expected" to be played in the Treble Clef measure above within the same octave, to avoid confusion, notation of Accidentals is usually repeated in the Treble Clef. In the case of multi-instrument and chorale scores, staves are much more independent, and Accidentals may freely appear in different staves of the same measure without expectation of repetition in other parts.
No. An accidental (a sharp, flat or natural that doesn't feature in the key signature, unless changed previously) only applies to that particular pitch of note, and only for that bar - unless tied across to the following bar.
If for example there was an accidental sharp on the C, bass clef, second space up, and a C note was featured on middle C, that middle C would be played as C natural. It would be unusual, but that's the case. If the writer wanted middle C to be sharp, that accidental would need to be written in for that note, too. Regardless of which hand played
There is the rare case where a note (of particular pitch, not just note name) had an accidental, and was played first by one hand, then the other, in the same bar, and here, one accidental would suffice for both hands.
EDIT: got a feeling we're all barking - up the wrong tree! This could well be asking about a # in the key signature ('a C# in the left-hand part of the staff') but there will also be a C# notated in the other staff, won't there?
No, once an accidental has appeared it stays in force until the end of the bar. If the note is tied, the accidental is not written again. In this instance, however, if the same accidental was written again in the same bar it would need to be marked.
Unlike, however, the key signature, an accidental only applies to the space or line where it appears.
Each accidental (♯, ♭ or ♮) that is written in the staff, works:
- Only for the same staff
- Only for the same octave
- Only for the rest of the measure
What might confuse you is that in piano music, there is a tendency to add lots of superfluous natural signs (so it's not hard to find an example where in one bar, you have, for instance a C#, then 10 bars, there is no dot in that particular line/space at all, and in the 11th bar, when there is a C (the sharp worked only until the end of the bar), they print a natural). In choral music, this tendency is a lot worse (like a natural in bass because 15 bars earlier, the soprano had a sharp at the same tone 3 octaves higher). But this happens only for naturals and you can ignore these. The sharps and flats do never work across staves/bars/octaves (until they are in key signature, of course).