The electro-optical responses of single wall carbon nanotube dispersions were measured in aqueous suspension as a function of tube length and chirality. Specifically, dichroism measurements were performed at multiple wavelengths in the UV, visible and near infrared relating to the absorbing van Hove transitions of individual nanotube chiralities; measurement of the electro-optical effect at the wavelength of an individual tube transition allows for the determination of the effect of chirality on the asymmetric polarizability. To determine the length dependence of the asymmetric polarizability, size exclusion chromatography was used to generate length sorted fractions of the DNA wrapped nanotubes. Measurable alignment of the nanotubes during the application of the field was observed for all applied fields greater than 15 kV/m (RMS) at 3 kHz; strong alignment, with nematic order parameters above 0.5, was achieved at higher field strengths. The characterization of the anisotropic polarizability is a large step towards exploiting this property for the directed manipulation of specific nanotubes.