The exposition of this book is simple yet vital and rigorous.This is to help Undergraduate Students find it easy to understand the subject matter about Planck's radiation theory and Laboratory determination of Planck's Constant. A simple but concise method and cheap apparatus are used to perform the experiment under laboratory conditions such that every student can do it with little or no assistance. Planck's law describes the electromagnetic radiation emitted by a black body in thermal equilibrium at a definite temperature and this is a pioneering result of Modern Physics and Quantum Theory. In 1900, Max Planck developed a theory of black body radiation that leads to an equation for intensity I(¿,T) as a function of wavelength ¿ and temperature T that is in complete agreement with experimental results at all wavelengths. Laboratory experiments were performed to determine Planck's constant using electric bulbs as sources of black body radiation, two colored optical filters,auto transformer,power source,phototransistor LRC-meter,etc. This book is vital because laboratory experiments under Modern Physics is an aspect of experiments which are rarely done in most Physics laboratories.