This textbook has been designed to meet the needs of B.Sc. Third Semester students of Physics as per Common Minimum Syllabus prescribed for Patna University and other Universities and Colleges under the recommended National Education Policy 2020 in Bihar. The book extensively covers important aspects of the modern-day course curriculum such as classical-, quantum- and statistical-based solutions to the most complicated problems in physics of micro-dimensional size. The book comprised of two theory papers 'Thermal Physics & Thermodynamics' and 'Electricity & Magnetism'. The theory part starts with Maxwell-Boltzmann Energy Distribution Law for an ideal gas followed by Degrees of Freedom, Law of Equipartition of Energy, Molecular Collisions, Mean Free Path, Transport Phenomenon. Subject further progresses to explain the Brownian Motion and Rectilinear Flow of Heat, Vander Waal's Equation for Real Gases, Jools-Thomson Effect, Zeroth, First, Second, Third Laws of Thermodynamics, Concept of Entropy and Thermodynamic Potentials along with nine laboratory experiments are incorporated pertaining to this paper.