3 micrometer (radius) scattering 12 micrometer (radius) scattering Air Resonance radius 3 = 1.1 MHz Air Resonance radius 6 = 530 kHz (typical albumen testing bubble) ________________________________________________________________________ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . For a gas with c = 343 m/s (air) . . . . . . . . . . . . . . . . . . . (hard sphere in air) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ka = 1 gives f = 18 MHz ka = 1 gives f = 9.1 MHz ka = 2 gives f = 36 MHz ka = 2 gives f = 18 MHz ------------------------------- ------------------------------- ka = 5 gives f = 91 MHz ka = 5 gives f = 46 MHz ------------------------------- ------------------------------- ka = 10 gives f = 180 MHz ka = 10 gives f = 91 MHz 1 MHz gives ka = 0.055 1 MHz gives ka = 0.11 2 MHz gives ka = 0.11 2 MHz gives ka = 0.22 ------------------------------- ------------------------------- 10 MHz gives ka = 0.55 10 MHz gives ka = 1.10 ------------------------------- ------------------------------- 100 MHz gives ka = 5.5 100 MHz gives ka = 11 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ========================================================================= ============= For a fluid with c = 1500 m/s (water) ================ . . . . . . . . (hard sphere in air) . . . . . . . . . . . ============= (for an air bubble in water) ================ ========================================================================= ka = 1 gives f = 80 MHz ka = 1 gives f = 40 MHz ka = 2 gives f = 160 MHz ka = 2 gives f = 80 MHz ------------------------------- ------------------------------- ka = 5 gives f = 400 MHz ka = 5 gives f = 200 MHz ------------------------------- ------------------------------- ka = 10 gives f = 800 MHz ka = 10 gives f = 400 MHz 1 MHz gives ka = 0.013 1 MHz gives ka = 0.025 2 MHz gives ka = 0.025 2 MHz gives ka = 0.050 ------------------------------- ------------------------------- 10 MHz gives ka = 0.13 10 MHz gives ka = 0.250 ------------------------------- ------------------------------- 100 MHz gives ka = 1.3 100 MHz gives ka = 2.50 ka_i = 2 pi (radius in microns) (freq in MHz) / (c in meters/sec) f_i = (c in meters/sec) (ka) / 2 pi (radius in microns) ka = (2 pi / wavelength in microns) * (radius in microns)