In this manuscript the core-shell nano particle under quasi static approximation was modeled for extinction spectra and resonance peak position. The extinction and resonance frequencies were found tunable under the influence of shape, size and dielectric constant of the surrounding media. The Plasmonic peak positions showed a red shift with increasing shell size. Conversely, when shell size is kept fixed with Cesium diameter increasing, a blue shift was observed. The tenability of Plasmonic peak position by varying core-shell dimension or surrounding media in Cs-Au nano-rods has been established here by theoretical evaluation.