Insert "&id=1" in $.get("test.php", ?

Insert "&id=1" in $.get("test.php", ?

As the headline says, I want to insert, for example &id=1 in the test.php-URL...
  1. $.get("test.php",
That works...
  1. $.get("test.php&id=1",
This don't, do I have to seperate the &-sign o how does it work?