The whole text has been arranged strictly according to N.C.E.R.T. Pattern. To Provide clarity of the subject, the whole text is studded with The Jargon, Key point, Watch out and Self-test Question Window to Formula forms a new feature of the present revised edition. It contains a direct and simple formula based Numerical Problem, which will tell the students as to how the formula derived in an article is to be used to solve the problem. The article work in each chapter of unit is coupled with well graded and carefully selected Solved Numerical Problems. These Solved Numerical Problems have been categorized into two Parts. I from Board Examinations and II from Competitive Engineering Examinations, such as I.I.T., Roorkee and I.S.M., Dhanbad. Many such problems have been provided with solutions by adopting a novel technique in the form of Thought Process.