Question

The angle of dip at a place on the earth gives
(A) Horizontal component of earth’s magnetic field.
(B) The location of geographical meridian.
(C) The vertical component of earth’s magnetic field.
(D) The direction of earth’s magnetic field.

Answer 1

Hint
Using the angle of dip definition we will show how the magnetic field is a vector quantity and resolved in different components. After that we will understand how different components of earth’s magnetic field are related to the ground.
By analysing these factors, we will be able to find what the angle of dip at a place on the earth gives and then we will choose the correct option.

Complete step by step answer
Angle of dip is the angle built by the magnetic field of earth with the horizontal, i.e. the earth surface. It tells the direction of the earth's magnetic field.
Magnetic field being a vector, can be resolved into horizontal and vertical components. The horizontal component we get after resolution is parallel to the ground, so there is no question of any angle associated with it.
At any point on the earth surface, a geographical meridian always passes through it. It has no relation with the magnetic field. Whereas, the angle of dip is a parameter of the field.
The vertical component of the earth's magnetic field is always perpendicular to the ground, so the angle is always $90^\circ$ .
Hence, we see that the angle of dip gives the direction of earth’s magnetic field.
So, the correct option is (D).

Note
Angle of dip is the angle made by the earth's total magnetic field $\overrightarrow B$ with the horizontal direction in the magnetic meridian, so Its value is different for different places. Also note that at a place on the poles, earth’s magnetic field is perpendicular to the surface of earth and at equator earth’s magnetic field is parallel to the surface.