Abstract: The working principles of ballistic galvanometer is introduced and the movement state of its de＇ flection coil in the magnetic field is analyzed. Some mathematical and physical methods and electromagnetical knowledge are used to deduce physical formulas for various movement states, and to reveal the movement laws of deflecting coil, which exerts great significance on apparatus adjusting and experimental circuit designing.

Key words: ballistic galvanometer, coil, moment of force, damping