As you turn it, you can work with a different frequency at a time, but you can not hear others. In the old days the Capacitor was called a condenser, but we don't use that name anymore. A capacitor is a special electrical component that you can use to charge it with electrons, or energy in the circuit. Once you charge the capacitor to it's maximum, it stays charged until you discharge it. It was called a capacitor, because this device possesses capacitance.
Capacitance is the inherent property of electric circuit that opposes change in voltage.
Property of circuit whereby energy may be stored in electrostatic fields and use to do something with later on or immediately. A potential voltage connected across these plates produces the following action. I did this picture below to illustrate my example better in Photoshop. The electrons from the negative battery terminal or lower potential terminal flow through the wire instantaneously to the capacitor and hit plate A of the two plates, A and B or 1 and 2. The electrons are distorted toward the positive plate.