A magnetic compass needle oscillates $30$ times per minute at a place where the dip is $45^o$, and $40$ times per minute where the dip is $30^o$. 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
$3.6$
$1.8$
$2.2$
$0.7$
The lines joining the places of the same horizontal intensity are known as
Earth's magnetic field always has a horizontal component except at or Horizontal component of earth's magnetic field remains zero at
What was the recognition of Earth’s magnetic field ? State dynamo effect
A dip needle lies initially in the magnetic meridian when it shows an angle of dip $\theta $ at a place. The dip circle is rotated through an angle $x$ in the horizontal plane and then it shows an angle of dip $\theta '$. Then $\frac{{\tan \theta '}}{{\tan \theta }}$ is
The angle of dip at a certain place on earth is $60^o$ and the magnitude of earth's horizontal component of magnetic field is $0.26\, G$. The magnetic field at the place on earth is.....$G$