Write a query in SQL to obtain the name of the physicians who are the head of the department

Write a query in SQL to obtain the name of the physicians who are the head of the department.

Sample table: physician

employeeid |       name        |           position           |    ssn
------------+-------------------+------------------------------+-----------
          1 | John Dorian       | Staff Internist              | 111111111
          2 | Elliot Reid       | Attending Physician          | 222222222
          3 | Christopher Turk  | Surgical Attending Physician | 333333333
          4 | Percival Cox      | Senior Attending Physician   | 444444444
          5 | Bob Kelso         | Head Chief of Medicine       | 555555555
          6 | Todd Quinlan      | Surgical Attending Physician | 666666666
          7 | John Wen          | Surgical Attending Physician | 777777777
          8 | Keith Dudemeister | MD Resident                  | 888888888
          9 | Molly Clock       | Attending Psychiatrist       | 999999999

 departmentid |       name       | head
--------------+------------------+------
            1 | General Medicine |    4
            2 | Surgery          |    7
            3 | Psychiatry       |    9