# Physics Equations

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1. Pressure (pascals) =
• Force (Newtons)
• ______________
• area (cm²)
2. Relationship between frequency and period
they are reciprocals

Period(s) = 1/frequency(Hz)

Frequency(Hz) = 1/period(s)
3. frequency x period =
1
4. Relationship between power and amplitude
Power (W) = Amplitude² (dB²)
5. Intensity (W/cm2)=
• Power (W)
• _______________
• beam area (cm2)
6. Wavelength (mm) =
• Propagation Speed (mm/μs)
• ________________________________
• frequency (MHz)
7. Wavelength in Soft Tissue =
• 1.54 mm/μs
• _______________
• frequency (MHz)
8. Speed (m/s)=
frequency (Hz) x Wavelength (m)
9. Pulse duration (μsec)=
cycles in a pulse x period (μsec)
10. Pulse duration (μsec) =
• # of cycles in a pulse
• __________________
• frequency (MHz)
11. PRP x PRF =
1
12. Relationship between Pulse Repetition Period (sec) and Pulse Repetition Frequency (Hz)
Reciprocals.

• PRP = 1/PRF
• PRF = 1/PRP
13. Duty Factor(%) =
• Pulse Duration (msec)
• _________________________ x 100
• Pulse Repetition Period (msec)
14. Spatial Pulse Length (mm) =
# of cycles x wavelength (mm)
15. Total Attenuation (dB) =
path length (cm) x attenuation coefficient (dB/cm)
16. Impedance (Rayls) =
Density (kg/cm3) x propagation speed (m/s)
17. Incident Intensity (dB/cm2) =
reflected intensity + transmitted intensity
18. Intensity reflection coefficient (%) =
• Z- Z1
• (________ ) 2     OR
•     Z+ Z1

[(Z2-Z1)/ (Z2+Z1)]2
19. Incident transmission coefficient (%) =
• Transmitted Intensity
• __________________ x 100
• Incident Intensity
20. Intensity Transmission Coefficient (%) =
100% - Intensity Reflection Coefficient
21. Transmitted Intensity =
Incident Intensity x Intensity Transmission Coefficient
22. Snell's Law:
• sin (angle of transmission)      propg. speed 2
• _____________________  =  ______________
• sin (angle of incidence)           propg. speed 1
23. Frequency (Hz) =
attenuation coefficient x 2
24. distance to boundary (mm) =
• go-return time (μs) x speed (mm/μs)
• ________________________________
• 2
25. Bandwidth =
Maximum Frequency - Minimum Frequency
26. Quality Factor =
• resonant frequency (MHz)
• ______________________
• bandwidth (MHz)
27. Frequency of a Pulsed Transducer (MHz) =
• material's propagation speed (mm/μs)
• ________________________________
• 2x thickness (mm)
28. Attenuation coefficient (dB/cm2)=
1/2 Frequency (MHz)
29. To find the depth or time of flight in soft tissue:
• depth = 1.54 (mm/μs) x go-return time (μs)
•             _____________________________
•                        2
30. Pulse Repetition Period in soft tissue (μs) =
imaging depth (cm) x 13(μs/cm)
31. Pulse Repetition Frequency in soft tissue (Hz) =
• 77,000 (cm/s)
• _________________
• imaging depth (cm)
32. Time of flight (μs) =
depth (cm) x 13μs
33. Axial Resolution (mm) =
• spatial pulse length (mm)
• ______________________
•     2
34. Axial Resolution (mm) =
• 0.77 x # of cycles in pulse
• ______________________
• frequency (MHz)
35. Frame Rate =
• 1
• __
• T
36. Tx Frame Rate =
1
 Author: Nelikya ID: 255050 Card Set: Physics Equations Updated: 2014-01-03 22:26:02 Tags: Spi Folders: Description: spi Show Answers: