BRAINCAKEReflection at Boundaries
When ultrasound travels from a medium of acoustic impedance Z1 into one of Z2, part of it is reflected at the boundary. For a beam hitting the boundary at right angles, the fraction of the intensity reflected (the intensity reflection coefficient) is
Ir / I0 = (Z2 − Z1)2 / (Z2 + Z1)2
Ir is the reflected intensity and I0 the incident intensity. The rest of the intensity is transmitted, so the fraction transmitted is 1 − Ir/I0.
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Key terms in this lesson
- acoustic impedance
- The product of the density of a medium and the speed of sound in it, which determines how much ultrasound is reflected at a boundary.
More in Medical Imaging
- PET Scanning
- Ultrasound
- The Piezoelectric Effect
- Ultrasound Transducers
- A-scans and B-scans
- Acoustic Impedance
- Impedance Matching and Coupling Gel
- Doppler Imaging
All 20 lessons in Medical Imaging · All OCR A-level Physics topics