Dip circle can be used to determine the angle of dip at a place . Dip circle consists of a magnetic needle free to rotate in a vertical plane . The end points of the needle move over a vertical circular scale . This arrangement can rotate about vertical axis . The angle rotated about vertical axis can be read from a horizontal scale .
If the dip circle is now rotated about vertical axis by `90^(@)` .Now the needle is at `60^(@)` from vertical . The angle of dip at that place is
A. `30^(@)`
B. `60^(@)`
C. `90^(@)`
D. `150^(@)`
