How does electromagnetic calling bell work?
The bell has a core of copper wire wound around the core ,through the center of the core is an iron rod with a soft spring at one end of the rod to keep it taught . When voltage is applied to the copper wire it will induce a magnetic field around the core which will cause the iron rod to move against the spring pressure and strike a metal plate that causes the Ding in a Ding Dong bell , after the voltage is terminated by letting go of the door bell the spring causes the iron rod to slid back through the core to hit another metal plate causing the Dong sound .
