Acoustic Concepts, Class 2
- An electrical current traveling through a wire generates a magnetic field. (In other words, it creates an electromagnet.)
- Reversing the polarity of an electrical current reverses the polarity of an electromagnet.
- The changing polarity of an alternating current in an electromagnet can be used to move a permanent magnet back and forth to create a linear motor.
- The frequency of the alternating current determines the rate of movement of the linear motor.
- At lower rates (less than 20 cycles per second) the back-and-forth movement is visible. At higher rates (greater than 60 cycles per second) the back-and-forth movement cannot be seen, but is experienced as sound.
- An electrodynamic speaker is a specialized version of a linear motor.
- The speaker cone amplifies the sound, making it louder.