what is the angle of dip?
If a non-magnetic piece of metal like copper is suspended at its center of gravity, the copper plate remains horizontally in equilibrium. If on the other hand, a magnetic needle is suspended at its center of gravity so that it is free to take up any position in the magnetic north-south plane, it makes an angle.
The earth’s magnetic field is not parallel to the earth’s surface excepting at the magnetic equator. As a result, excepting at the magnetic equator, a freely suspended needle makes an angle with the horizontal.
The angle between the horizontal and the earth’s magnetic field is known as angle of dip.
The angle of dip is different at different places on the surface of the earth. At the magnetic equator it is 0o and increases and at the magnetic pole it becomes 90o.
You would be surprised to know that, though scientists have not been able to discover the mechanism, some of the migratory birds are capable of detecting changes in the angle of dip as well as angle of declination. This helps them in navigating long distances while they migrate.