This book is aimed at colleagues and students of the third grade of high school. It includes: Electromagnetic waves and elements of quantum mechanics, which according to the new curriculum will be taught in the physics lesson of the third grade of high school. This material is divided into units, each of which contains: Theory, Critical questions, Computational issues. At the end, there are five simulation exams, in this effort the help of my collaborator Ms. Vivi Betsiou was significant, whom I thank. I will gladly accept any observation that will contribute to the improvement of this book.