ARUN KUMAR, Ph.D., is Associate Professor in the University Department of Physics, Ranchi University, Ranchi. He has been teaching physics and electronics to undergraduate and postgraduate students for over two decades. Basic Electronics, Number Systems—For Digital Computers and Problems in Physics are three other books authored by him. He has published a number of papers in journals of international repute and has supervised students for their Ph.D. degree. He is a Fellow of the Institution of Electronics and Telecommunication Engineers (IETE) and currently Vice Chairman of its Ranchi centre, and a Member of the Indian Associations of Physics Teachers (IAPT), Kanpur. Dr. Kumar is also listed in ‘Reference Asia: Asia’s Who’s Who of Men and Women of Achievement’.