PGP key passphrase change

[Erw]

Hello,

If I change my private PGP passphrase, does this affect my public key?

(Do I have to update it and is the previous one useless or not?)

If not, does this mean, that if I have an old private key, with the old passphrase, I can still use it beside the new one?

Thanking you in advance,

Erwin