Do signature alterations apply also to notes on ledgers?

[amc252]

Hello everyone,

this might be an utterly stupid question, but I'm a total beginner so here it goes.
Do the alterations indicated in the signature key apply also to notes on the ledgers above and below the staff?
Meaning, if the signature key indicates a # on, say, A (second space from below) and then the sheet has a note A an octave higher (first ledger line above the staff) would that A note be # or natural?
Also, the C central between the treble and bass keys on a piano music sheet is natural or takes the alteration on the signature on either key?

Thanks in advance for clearing my doubts.

[lelle]

There are no stupid questions, if you don't know you don't know.

The sharps or flats indicated by the key signature apply to all the notes of the same name on the entire piano. So if there is an F sharp in the key signature, all F:s on the entire piano become F sharps.

Accidentals applied to an individual note apply to that pitch only, for the rest of the bar only.

[amc252]

Thanks a lot,
it makes sense and clarifies my doubt entirely.