A-Level Physics OCR A H556

6.5.3: Using ultrasound

#6.5.3a

ultrasound; longitudinal wave with frequency greater than 20 kHz

#6.5.3b

piezoelectric effect; ultrasound transducer as a device that emits and receives ultrasound

#6.5.3c

ultrasound A-scan and B-scan

#6.5.3d

acoustic impedance of a medium; $Z = ρc$

#6.5.3e

reflection of ultrasound at a boundary; $\dfrac{I_r}{I_0} = \dfrac{(Z_2 - Z_1)^2}{(Z_2 + Z_1)^2}$

#6.5.3f

impedance (acoustic) matching; special gel used in ultrasound scanning

#6.5.3g

Doppler effect in ultrasound; speed of blood in the patient; $\dfrac{Δf}{f} = \dfrac{2v\cos{θ}}{c}$ for determining the speed v of blood.

6.5.2

Diagnostic methods in medicine