  We present a simple permanent magnet set-up that can be used to measure the
Faraday effect in gases, liquids and solids. By fitting the transmission curve
as a function of polarizer angle (Malus' law) we average over fluctuations in
the laser intensity and can extract phase shifts as small as $\pm$ 50
$\mu$rads. We have focused on measuring the Faraday effect in olive oil and
find a Verdet coefficient of $V$ = 192 $\pm$ 1 deg T$^{-1}$ m$^{-1}$ at
approximately 20 $^{\circ}$C for a wavelength of 659.2 nm. We show that the
Verdet coefficient can be fit with a Drude-like dispersion law $A/(\lambda^2 -
\lambda_0^2)$ with coefficients $A$ = 7.9 $\pm$ 0.2 $\times$ 10$^{7}$ deg
T$^{-1}$ m$^{-1}$ nm$^2$ and $\lambda_0$ = 142 $\pm$ 13 nm.
