### Quick Reference:

**Period x Frequency**= 1**Intensity**(W/cm2) = Power (w) / Area (cm2)**Wavelength**(mm) = Propagation Speed / Frequency (MHz)**Propagation Speed**(m/s) = Frequency (Hz) x wavelength (m)**Pulse Duration**(us) = # cycles X period (us)**Pulse Duration**(us) = # cycles / Frequency (MHz)**Spatial Pulse Length SPL**(mm) = # cycles X Wavelength (mm)**PRP**= 1 / PRF**PRF**= 1 / PRP**PRF x PRP**= 1**Duty Factor**(%) = Pulse Duration / Pulse Repetition period X 100**Total Attenuation**(dB) = Attenuation Coefficient (dB/cm) X Distance**Attenuation Coefficient**(dB/cm) = Frequency (MHz)/2**Attenuation Coefficient**(dB/cm) = 0.5dB / cm / MHz**PRP**= imaging depth (cm) X 13 microseconds / cm**PRF**(Hz) = 77,000 cm / s / imaging depth (cm)**Axial resolution**(mm) = SPL (mm) / 2**Axial resolution**(mm) = (wavelength (mm) X # cycles in pulse) / 2**Axial resolution**(mm) = 0.77 x #cycles in pulse / Frequency (MHz)**Near Zone Length**(mm) = Diameter (squared) (mm) / 4 x wavelength (mm)

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#### Franco

Founder at ExamRefresh

I am the founder and lead Instructor here at ExamRefresh.com. I strive to help those that are entering the field of Ultrasound to be the best that they can be. Ultrasound is my passion.

#### Latest posts by Franco (see all)

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- Period and Frequency equations - August 5, 2013

Hello there, thank you for your videos, they have been helping my classmates and I very much. We will be taking the SPI on August 7. We are all very nervous about this test. Keep up the great work :)

Thank you so much. Good luck on your tests. If you need any help feel free to ask.