Human biological functions or health care practices have basis of principles of biophysics. Therefore, nurses involved in providing nursing care must understand the physical principles and their applications in health care practices. So that, nurses can assess, plan, implement and evaluate each care intervention more effectively and scientifically. This textbook Biophysics in Nursing is a modest attempt to bring about the basic physical principles in simple, non-mathematical approach by incorporating their applications to health care and nursing practices. It has been ensured that each physical principle is simply defined and discussed with its application to nursing practices. Each topic of the content is presented in simple and lucid manner by using the illustrations and examples in health care and nursing practice areas.