Basic characteristics of speakers

(1) Speakers have two terminals (two leads). When a single speaker is used, the two pins are not polarized. When multiple speakers are used at the same time, the two pins are polarized.
(2) Speakers have a paper cone, which is usually black, but also white.
(3) Speakers come in several shapes, including round, square, and oval.
(4) There is a magnet on the back of the speaker cone. When a metal screwdriver is used to touch the magnet of an external magnetic speaker, you can feel the presence of magnetism. There is no such feeling in an internal magnetic speaker, but there is a magnet inside the shell.
(5) Speakers are installed on the machine panel or in the sound box.