We give sufficient explanation for every quantum system described. Quantum systems are real and there are many exam-
ples to adduce this fact. Students are expected to have basic knowledge of classical mechanics. The calculations are

presented with sufficient steps for the student to follow up to the final stage.
We also give numerical examples and exercises for each and every chapter of the book. This is intended to give students,
who are new to the subject, a better feel of the concepts and formulae discussed in the text. In the end, we hope that this
will help students have the much needed practice, using the different formulae and hypotheses to solve numerical
problems. It is the latter that according to our experience has led many students to consider not only quantum mechanics,
but theoretical physics as a hard subject. Some of the features in the book are examples and applications showing that
quantum mechanics is not abstract but a rather an integral part of our daily lives. There are a few sections which appear
to be a little advanced. These are included for completeness. A curious student may read those sections too.
The authors are grateful to Prof. Ezra K. S. Mugambe for his comments drawn from his long experience of teaching
quantum mechanics at both undergraduate and postgraduate levels. We would like to thank the physics major students
of the years between 2000 and 2016 who attended the quantum mechanics lectures. Their comments helped us to
improve the earlier versions of this monograph, particularly, to include some illustrations in the text.