Verdet's constant apparatus is used to measure the wavelength dependence of Verdet's constant for several materials. The Verdet's constant is an optical constant that describes the strength of the Faraday effect for a particular material. While being constant for most materials, the Verdet's constant is extremely small and is wavelength dependent.

OPTIMUM PARAMETERS FOR A CONSTANT DEVIATION MAGNETIC SPECTROGRAPH M. N. VISWESVARIAH and N. SARMA Bhabha Atomic Research Centre, Trombay, Bombay 74, India Received I I January 1968 In this paper certain aspects of the ion optics of a constant deviation magnetic spectrograph are presented and fresh criteria applied to optimise source distance The inverse of the spectral resolution is equal to the expression describing the non-relativistic Doppler shift: 1 / R = ?? / ? = v / c, where v is the radial velocity of the source and c is the speed of light. Hence a spectral resolution of R = 10,000 would enable a wavelength shift of ?? = 0.0001 x ? to be measured, which implies that only Doppler shifts larger than v = 0.0001c = 30 km • This "zeroth order" maximum is of no use, because it does not provide any discrimination in wavelength, it is at the same angle for any ?! • Gratings are designed to concentrate radiation in orders with m ? 0 (note that positive and negative m are equivalent)! using spectrograph built by undergrad student may be approximated by the Hartmann dispersion formula. A, B and C are known as the Hartmann constants . 10 . For a given l, the deviation angle is q 11 position of minimum deviation (of q) 16 q i 1 Diffraction gratings are manufactured either classically with the use of a ruling engine by burnishing grooves with a diamond stylus or holographically with the use of interference fringes generated at the intersection of two laser beams (for more details see Diffraction Gratings Ruled & Holographic Handbook). Use the grating equation with d=(1/6000) cm to find the wavelength for each