At a certain place,the angle of dip is $30^{\circ}$ and the horizontal component of the Earth's magnetic field is $0.50 \text{ Oersted}$. The Earth's total magnetic field is:

The angle of dip is $90^{\circ}$ at:

$A$ line passing through places having zero value of magnetic dip is called

If the angle of dip at places $A$ and $B$ are $30^{\circ}$ and $45^{\circ}$ respectively,the ratio of the horizontal component of the Earth's magnetic field at $A$ to that at $B$ will be.
$[\sin 45^{\circ}=\cos 45^{\circ}=\frac{1}{\sqrt{2}}, \quad \sin 30^{\circ}=\frac{1}{2}, \quad \cos 30^{\circ}=\frac{\sqrt{3}}{2}]$

What is the dynamo effect?

$A$ magnet hung at $45^{\circ}$ with the magnetic meridian makes an angle of $60^{\circ}$ with the horizontal. The actual value of the angle of dip is.