What is the angle of dip, when the horizontal and vertical components of magnetic field of earth's are equal and how?
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.
Just like geographic equator, there is a magnetic equator as well. There is no vertical component at points lying on the magnetic equator. Thus, at points on Earth which lie on magnetic equator, the angle of dip is equal to zero.
So the required angles of dip are 0 and 90°.