The whispering gallery modes (WGMs) of a microcavity are sensitive to its refractive index and size. WGMs find applications in micro-lasing, add-drop filter, sensing, Raman spectroscopy, non-linear optics and cavity quantum electrodynamics. The radiative rate of the emitter can also be modified in the presence of a cavity. Cavity effects are proposed to be studied in newly synthesized quantum dots and nitrogen vacancy centres embedded in spherical microbeads. WGMs of another microbottle-shaped cavity are also proposed to be investigated for sensing applications.