Physics Formulas Flashcards
Period (T) (µs)
Period (T) = 1/frequency
Wavelength (lambda)(mm)
Wavelength (mm) = propagation speed (mm/microsecond)/frequency (MHz)
Power (W)(mW)
Power (mW) = Amplitude (A) squared (dB)
What is the Power with 1/2 Amplitude
Power (mW) = 1/4
[A= 1/2 (square denominator)]
[A= 1/3 (P= 1/9)]
Intensity (I) [(m)W/cm squared]
Intensity = Power/Area
Beam Uniformity Ratio (BUR)
BUR = SP/SA (Spatial Peak/Spatial Ave.)
Impedance (Z)(rayl)
Impedance = Density (kg/m cubed) x propagation speed (m/s)
Intensity Reflection Coefficient (IRC)
IRC = [(Z2-Z1)/(Z2+Z1)] squared
Intensity Transmission Coefficient (ITC)
ITC = 1-IRC
Reflected Angle always equals what?
Incidence Angle
Attenuation Coefficient (dB/cm)
Attenuation Coefficient = 0.5 x frequency (MHz)
Total attenuation (dB)
Total attenuation = 0.5 x frequency x path length
Quality Factor (Q factor)
Q factor = Operating frequency/Bandwidth
1 Near Zone Length
1 Near Zone Length = 1/2 transducer diameter
Axial Resolution (mm)
Axial Resolution = spatial pulse length/2
Elevational Resolution
Elevational Resolution = Beam thickness
Range Equation (Distance to Reflector) (mm)
Range (Distance) = 1/2 x (propagation speed x pulse round-trip time)
Abbreviated Range Equation
Range (D) = 1/2 CT [Constant Time (Propagation Speed)]
Nyquist Limit
Nyquist Limit = PRF/2
Pulse Repetition Frequency (PRF)(kHz)
PRF = 1/PRP (ms)
or
PRF = lines per frame x frame rate (Hz)
Pulse Repetition Period (PRP)(ms)
PRP = 1/PRF (kHz)
Pulse Duration (PD)(µs)
PD = # of cycles in a pulse x period (T)
Spatial Pulse Length (SPL)(mm)
SPL = # of cycles in a pulse x wavelength
Duty Factor (DF)
DF = PD/PRP
Shades of Gray
Shades of Gray = 2ª (a=x)
4 bit = 2x2x2x2= 16 shades of gray
Binary Code uses what values? How would you write 17?
1,2,4,8,16,32,(doubles); 17 = 1 0 0 0 1
Doppler Shift
Doppler Shift = (2 x velocity (RBC) x transmit frequency x Cos of angle)/ C (propagation speed)
RBC=Red Blood Cell
Cos=Cosine
C=Constant
T
Period
Lambda
Wavelength
A
Amplitude
P
Power
I
Intensity
BUR
Beam Uniformity Ratio
Z
Impedance
IRC
Intensity Reflection Coefficient
ITC
Intensity Transmission Coefficient
dB
decibels
Q factor
Quality Factor
LARRD
Axial Resolution (Longitudinal, Axial, Range, Radial, Depth)
LATA
Lateral Resolution (Lateral, Angular, Transverse, Azimuthal)
PRF
Pulse Repetition Frequency
PRP
Pulse Repetition Period
PD
Pulse Duration
SPL
Spatial Pulse Length
DF
Duty Factor