Electromagnet Buzzers and Telegraphs

Students can see that the direction of the magnetic field is different depending on the direction of the current flow, understand that a magnetic field is generated when current flows through changes in the magnetic field generated around a ring-shaped wire (coil), and use this to know that an electromagnet becomes an electromagnet when a soft iron rod such as a nail is placed in a coil with a current flowing through it, and use it to make a buzzer that vibrates and makes a sound.