A magnetic compass needle 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 :

a) |
2.2 |
b) |
0.7 |

c) |
3.6 |
d) |
1.8 |

A magnetic compass needle 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 :

a) |
2.2 |
b) |
0.7 |

c) |
3.6 |
d) |
1.8 |

1 Answer

127 votes

T_{1} = 2 sec., T_{2} = 3/2

For place (1),

For place (2),

T = =

= ⇒ =

⇒ = 0.68 0.7

127 votes

127