Light is a wave, kind of like a wave in the ocean. These light waves carry energy. This energy can do many interesting things, like help grow a plant, produce electric currents, or cause chemical reactions. Light carries a different amount of energy depending on its wavelength. main objective of this lecture is to present on Light: Lasers, Holograms and Spectroscopy. Spectroscopy is the study of the spectrum from different atoms and molecules. Since different kinds of light have slightly different spectra, scientists can use a star’s spectrum to figure out what elements it is made of.