An oscillating diaphragm which is dissipating acoustic energy to the air absorbs this energy from the oscillating system. This is comparable with a resistance which converts electrical energy into heat and dissipates it into the surroundings. The efficiency with which a diaphragm converts its physical energy into acoustic energy, is described by its radiation resistance Zr. The radiation resistance of a diaphragm is subdivided into: - effective component (sound radiation) - wattless component I. The radiation resistance depends on the frequency and the surface area of the diaphragm. The greater the diaphragm area, the greater the radiation resistance. This means that the larger diaphragm areas will be better suited to reproducing low frequencies.