Figure 4
From: Dipolar colloids in apolar media: direct microscopy of two-dimensional suspensions
Brownian rotation of the colloids (at η → 0) is limited by the external electric field Eext.
In particular, the standard deviation β of the projection of the dipole on the horizontal plane is reduced for high Eext, indicative of the presence of permanent dipoles. The theoretical fit, for a permanent dipole in a field, is shown with a solid curve. Note that the overall agreement of this model with the experimental data is better than for a more complex model, where an induced dipole couples to (possible) particle anisotropy (red dashes).
