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Measuring the Faraday effect in olive oil using permanent magnets and Malus' law.

Carr, Daniel Luke and Spong, Nicholas L. R. and Hughes, Ifan Glyndwr and Adams, Charles S. (2020) 'Measuring the Faraday effect in olive oil using permanent magnets and Malus' law.', European journal of physics., 41 (2). 025301.


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 short-term fluctuations in the laser power and can extract phase shifts as small as ± 50 μrads. We have focused on measuring the Faraday effect in olive oil and find a Verdet coefficient of V = 192 ± 1 deg T-1 m-1 at approximately 20 °C for a wavelength of 659.2 nm. We show that the Verdet coefficient can be fit with a Drude-like dispersion law A / (λ2 - λ0 2) with coefficients A = 7.9 ± 0.2 × 107 deg T-1 m-1 nm2 and λ0 = 142 ± 13 nm.

Item Type:Article
Full text:(AM) Accepted Manuscript
Available under License - Creative Commons Attribution Non-commercial No Derivatives.
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Publisher statement:The deposited file will be available for reuse under a CC BY-NC-ND 3.0 licence after a 12 month embargo period from the date of publication.
Date accepted:24 October 2019
Date deposited:25 October 2019
Date of first online publication:13 January 2020
Date first made open access:13 January 2021

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