Notes of Chapter 17: Physics of Solids of “Physics XII” for FSc Part 2 published by Punjab Textbook Board, Lahore. These notes are very helpful to prepare Physics paper of FSc Part 2 for Federal Board, Multan Board, Faisalabad Board, Sargodha Board, Gujranwala Board, DG Khan Board, Rawalpindi Board or any other board of Punjab, Pakistan.

The solids in which the atoms, ions and molecules are arranged periodically are called crystalline solids.The crystalline solids show the phenomenon of X-ray diffraction.Every crystalline solid has sharp melting point i.e., for every crystal there is a temperature at which the thermal vibrations becomes so great that the structure suddenly breaks up, and the solid melts.