Ashish Arora is a distinguished academician, author, guide & Physics guru at International level.He has been mentoring students for IT JEE, NEET & IPhO since 1992. Many of his students have secured under Top 10 AIRs in various years' IT JEE & NEET including AIR 1 multiple times and won several GOLD & SILVER medals in IPhO in various countries.This book of PHYSICS GALAXY is a result of deep stress and serious efforts of the brain of Ashish Arora to develop fundamental understanding in Physics.The book, Physics Galaxy Vol. 4 consists of detailed theory, illustrations & practice questions on:Chapter-1: Atomic PhysicsChapter-2: Photo Electric Effect & Matter WavesChapter-3: X-raysChapter-4: Nuclear Physics and RadioactivityChapter-5: Geometrical OpticsChapter-6: Wave Optics