Voigt–Thomson law
# Voigt–Thomson law

Voigt–Thomson law describes anisotropic magnetoresistance effect in a thin film strip as a relationship between the electric resistivity and the direction of electric current:

       $\rho (\vartheta )=\rho _{0}+\Delta \rho \cdot cos^{2}\vartheta$

where:

    $\vartheta \$ is the angle of direction of current in relation to the direction of magnetic field
    $\rho _{0}\$ is the initial resistivity
    $\Delta \rho \$ is the change of resistivity (proportional to MR ratio)

The equation can also be expressed as:

       $\rho (\vartheta )=\rho _{\parallel }\cdot cos^{2}\vartheta +\rho _{\perp }\cdot sin^{2}\vartheta$

where:

    $\rho _{\parallel }\$ is the parallel component of resistivity
    $\rho _{\perp }\$ is the perpendicular component
