A Primary Method for the Determination of Ultrasonic Intensity with the Elastic Sphere Radiometer

An evaluation is carried out of the acoustic radiation force function Y = F _{r ^c} /(πa ² I), where F _r is the measurable radiation force on a sphere, c is the velocity of sound in the suspending medium, a is the radius of the suspended sphere, and I is the intensity of the plane progressive sound field incident upon the sphere. Comparison is made of the inelastic and elastic cases and experimentally verified for commercially available grade 10 type 440 C stainless steel ball bearings. It is concluded that for observations avoiding the resonance minima of Y, acoustic intensity can be determined with an absolute accuracy of about ±3%.