Prerequisites: PHYS 121/PHYS 121A or PHYS 122/PHYS 121A and MATH 112 with a grade of C or better. Elements of simple harmonic motion, wave motion, geometric and physical optics are considered. The wave and particle duality of nature is emphasized and made plausible by an examination of the important experiments and theories which lead to the modern concepts of matter and radiation. The conservation laws are broadened to include the equivalence of mass and energy.