how does the angle of dip vary from equator to poles?
Let us begin with the definition of magnetic dip.
Magnetic dip or magnetic inclination at a place is defined as the angle which the direction of the total strength of the earth’s magnetic field makes with horizontal line in magnetic meridian . It is represented by the symbol δ Dip circle is the instrument used for measuring the value of magnetic dip. See the figure below:
At different places on the surface of the earth δ is different. At the two magnetic poles, the magnetic needle rests vertically. Therefore , angle of dip at the two poles is 900. On the magnetic equator, the angle of dip is 0 as the needle would rest horizontally at the magnetic equator. At other places the value of dip angle lies between 0 and 90 degrees.
Therefore, the angle of dip from equator to the poles varies from 00 to 900.
Horizontal and vertical components of Earth’s magnetic field are equal at magnetic North and South poles. At these positions angle of dip will be 90° because direction of magnetic field of Earth is along the magnetic axis.