##### Equations for boards

Density

d = m/v

Pressure

p = F/A

wavelength

λ = c/f

SPL

SPL = λ * n

Pd

pd = n * period

DF ALL

DF = TA/PA

DF = pd * PRF

Intensity

Intensity = Power (W) / area (cm^{2})

Attenuation

Attenuation = 1/2 * f * pathlength cm

Distance

d = 1/2 * ct

Refraction transmission angle

New angle = (New c / Old c) * old angle

IRC

IRC = reflected/incident

IRC = (z_{2}
-z_{1}) / (z_{2} +z_{1})

impedance

impedance = density * c

Matching layer thickness

thickness = .25λ

Lateral Resolution

R_{L} = Beamwidth

Element thickness

1/2 λ

bandwidth

bandwidth = f_{max} - f_{min}

fractional bandwidth

fractional bandwidth = bandwidth/f_{O}

Q factor

Q_{f} = f_{O}/bandwidth

Doppler Shift

FD = (2 * Vcos*0* * f_{0})/c

Volumetric flow rate formula

Flow rate = V/t

pressure above the heart

above = CP - HP

Poiseuille's equation

flow = pressure*diameter/ strength*viscosity

steady flow
in a long straight tube

Reynolds #

R# = (average flow speed * diameter * density) / viscosity

NZL Formula

(D^{2} * f) / 6

Axial resolution

R_{A} = 1/2 SPL