A magnetic compass needl oscillates 30 times per minute at a place where the dip is `45^(@)` and
Channel: Doubtnut
Date: 2020-01-03

A magnetic compass needl oscillates 30 times per minute at a place where the dip is `45^(@)` and 40 times per minute where the dip is `30^(@)` if `B_(1)` and `B_(2)` are respectively the total magnetic field due to the earth at the two places then the ratio `B_(1)//B_(2)` is best given by