At which place, earth's magnetism become horizontal?

At which place Earth's magnetic field becomes horizontal?

At which place Earth's magnetic field becomes horizontal?

At which place on the earth, the earth's magnetic field becoes horizontal?

At a place on the surface of earth , the angle of dip is theta , intensity of earth's magnetism is I and the horizontal and vertical components of earth's magnetism are h and h' respectively . Then

A magnet suspended in earth's magnetic field can vibrated in horizontal plane. . A second magnet is so placed that the field becomes less than the horizontal component of earth's field. In this situatio, the time period will