Current Science

Basudev Roy ¹

Affiliations
1 Indian Institute of Science Education and Research, Kolkata 741 252, IN

Abstract

The richness of the sound emanating from a stringed musical instrument can be improved by the making it linger for longer. This has traditionally been performed in sitar and sarod by modification of boundary conditions while introducing a jawari. We try to understand the effect of the jawari by assuming periodic modulation of boundary conditions of the string in a sonometer and find that the lobe-like effect can indeed be observed as an interference between the frequencymodulated sideband of one mode with the next higherorder mode. The contributions from different modes can be added up. The size of the beat signal increases while increasing the depth of modulation.

Keywords

Beats, Boundary Conditions, Frequency Modulation, Note Richness, String Musical Instruments.

Full Text

   

Basudev Roy ¹, Erik Schaffer ¹

Affiliations
1 Centre for Plant Molecular Biology, University of Tübingen, Tubingen 72076, DE

Abstract

This communication presents a simulation study of the directed rotational motion of a birefringent spherical particle trapped in optical tweezers with randomly varying ellipticity of a trapping light at the point of threshold. When noise is not applied, the potential barrier due to the linear component of the polarization is simulated to be sufficient to prevent directed rotation till a certain threshold value of ellipticity. Random variations to the ellipticity cause random variations in the barrier height, including instants when the barrier is lower than the threshold energy level. It is due to this that the particle exhibits directed rotational motion at ellipticity lower than the threshold value. We also examine the rotational velocity of the birefringent particle as a function of the extent of zero-mean random noise applied to the ellipticity.

Keywords

Birefringent Particles, Barrier Height Rotational Motion, Washboard Potential.

Full Text