Expression of the variable capacity of the transducer
When an acoustic wave vibrates the mobile electrode of an electrostatic transducer, the inter-electrode distance d(t) varies: , where is the displacement of the mobile electrode. The electrical capacity of the transducer varies. The consequence is a voltage variation across the said capacitor.
The displacement modifies the capacity of the transducer as in the following formula Generally, the displacement is tiny compared to the rest position . Thus the capacity C(t) can be written: |