Abstract: By using the basic knowledge of mechanics and electromagnetism,we discuss the reasons why a charged particle,electrical dipole,dielectric,magnetic dipole,or paramagnetic material can not be suspended stably in a field and why a diamagnetic material can.Further,we introduce the details of the frog levitation experiment,which has been carried out by Geim,and its background physics.The explorations of such problem will not only intrigue students regarding to its perspective applications but also deepen their understanding to electrostatics and magnetism.

Key words: frog levitation, diamagnetic, magnetic levitation, stable equilibrium