Home 2nd Year Physics Notes Class 12 Physics Chapter 17 Notes – Physics of Solids

# Class 12 Physics Chapter 17 Notes – Physics of Solids

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In this post, I am sharing the Class 12 Physics Chapter 17 Notes PDF for the students of Intermediate Part 2. This chapter’s name is Physics of Solids. Students can download the Class 12 Physics Chapter 17 Notes PDF on their laptops or mobile. These Physics Notes are for all the boards working under the Punjab Board like Gujranwala Board, Lahore Board, Faisalabad Board, Multan Board, Rawalpindi Board, Sargodha Board, DG Kahn Board, and Sahiwal Board. Here are the complete FSC 2nd Year Physics Notes PDF chapters.

## FSC Part 2 Physics Chapter 17 Notes – Physics of Solids

Class 12 Physics Notes

#### Classification of Solids

Solids consist of the following types.

(1) Crystalline Solids

(2) Amorphous or Glassy Solids

(3) Polymeric Solids

#### Electrical Properties of Solids

The fundamenta electrical property of a solid is its ability to conduct electric current. The electrical behaviour of different solids is different. The solids are calssified into three groups regarding their electrical behabviour.

(1) Conductors

The solids which conduct electricity through them ae called conductors. e.h., Metals are conductors having conductivity of the order of 10-7.

(2) Insulators

The solids which do not conduct electricity through them are calledinsulatorsr. E.g., Wood, diamond etc. have conductivity ranging between 10-10 and 10-20.

(3) Semi Conductor

Those solids which have conductivity between conductors and insulators are called semi-conductors. e.g., Silicon and Germanium which have conductivity ranging from 10-6 to 10-4.

#### Energy Band Theory

Electron of an isolated atom are bounded to the nucleus and can have energy levels which are distinct. However when a large number of atoms say N, are brought close to one another to form a solid, each energy level of the isolated atom splits into N-sublevels, called states, under the action of the forces exerted by other atoms in the solid. Thses permissible energy states are discrete but so closely spaced that they apperar to form a continuous energy bands. In between two pemissible energy bands, there is range of energy states which cannot be occupied by electrons. These are called forbidden energy states and its range is said to be forbidden energy gap.