A general theory of passive linear electroacoustic transducers for which the surface velocity distribution is independent of the manner of excitation of the transducer is developed and applied to the calculation of important practical parameters of the transducer. A proof of the electroacoustic reciprocity theorem for such transducers is included. Another important theorem, the available acoustic power theorem, which states that the maximum power which can be absorbed by such a transducer from a plane wave sound field is given by the product of the intensity of the wave and the quantity λ2δR/4π where λ is the wave‐length of the wave and δRis the receiving directivity factor of the transducer relative to the direction of incidence of the wave is also proved. The paper concludes with a discussion of the available power efficiency of a transducer and its relation to the threshold pressure of the transducer.