Specific absorption rate (SAR)


Specific absorption rate calculates the rate at which energy is absorbed by the body when exposed to a radio frequency (RF) electromagnetic field. Specific absorption rate can also refer to absorption of other forms of energy by tissue, including ultrasound. It is defined as the power absorbed per mass of tissue.

Related formulas


SARSpecific absorption rate (in W/kg) (dimensionless)
Vsample mass (in kg) (dimensionless)
rposition (dimensionless)
σ(r)sample electrical conductivity (in S/m) (dimensionless)
E(r)RMS electric field (in W) (dimensionless)
ρ(r)sample density (in kg/m^3) (dimensionless)