Question 47 of 96

A magnet is suspended in such a way that it oscillates in the horizontal plane. It makes 20 oscillations per minute at a place where dip angle is 30o and 15 oscillations per minute at a place where dip angle is 60o. The ratio of total earth's magnetic field at the two places is

(a) 33:8                      (b) 16:93

(c) 4:9                           (d) 23:9