Physics in the Modern World: Student's Guide provides information pertinent to the fundamental concepts in physics. This book discusses several topics in physics, including atoms, molecules, compounds, elements, as well as the fundamental units of measure in science. Comprised of 21 chapters, this book starts with an overview of the standard units of measure for length, time, mass, energy, force, pressure, and density. This text then provides the meaning of various terms in physics, including atom, molecule, element, and compound. Other chapters explore the composition and behavior of all ordinary matter in which it depends on the four basic units, including electrons, protons, neutrons, and photons. This book discusses as well the method used for converting the units of physical quantities from one system of measurement to another. The final chapter deals with the various applications of radiation in biological investigations and in medical diagnostics and therapeutics. This book is intended for students enrolled in introductory physics courses.