[jQuery] looping through json

[iceangel89]

how can i loop through json like:

{ "departments": {
   "department": {"ID": 1, "Name": "Physics"},
   "department": {"ID": 2, "Name": "Chemistry"},
   "department": {"ID": 3, "Name": "Biology"}
}}

i tried

$.each(json.departments.department, function(i, n) {
        alert(i + " " + n);
});

and got

ID: 3
Name: Biology

but i wanted something like

1: Physics
2: Chemistry
3: Biology