When the movable plates of an air gang capacitor completely overlap the fixed-plates then the capacitance of this variable capacitor is:

When the movable plates of an air gang capacitor completely overlap the fixed-plates then the capacitance of this variable capacitor is Maximum.

Key Points A variable capacitor is a capacitor whose capacitance may be intentionally and repeatedly changed mechanically or electronically.

Variable capacitors are often used in L/C circuits to set the resonance frequency, e.g. to tune a radio (therefore it is sometimes called a tuning capacitor or tuning condenser), or as a variable reactance.

Maximum capacitance is achieved when the plates are "meshed" together, that is, they are inter-laced.

Minimum capacitance is achieved when the plates are "unmeshed", that is, they are not inter-laced.