Induction coil

An induction coil includes a first coil unit, a second coil unit, a third coil unit, a fourth coil unit, a fifth coil unit, a sixth coil unit, a seventh coil unit, an eighth coil unit, a ninth coil unit, a tenth coil unit, an eleventh coil unit and a twelfth coil unit all of which are arranged in a row. Each coil unit is a spring and comprises at least thirty coil bodies connected with each other and arranged in a stacked manner. The first, second, third, fourth, fifth, sixth, seventh and eighth coil units form a first coil module. The ninth, tenth, eleventh and twelfth coil units form a second coil module. The first coil module is connected with the second coil module. Therefore, when a magnet passes through the induction coil, the twelve coil units are simultaneously energized.