The main focus in atomic physics is on coherent effects in atomic systems such as zero and non-zero field magneto-optical resonances, level-crossing spectroscopy, alignment-to-orientation conversion, electromagnetically induced transparency, and others. Hyperfine structure and light-atom interactions in the presence of electric and magnetic fields are investigated experimentally and theoretically. Experiments are conducted in alkali atomic vapours using a wide range of lasers and signals are modelled using the optical Bloch equations for the density matrix. Applications to measuring electric and magnetic fields are also studied.