Home 2nd Year Physics Notes Class 12 Physics Chapter 18 Notes – Electronics

# Class 12 Physics Chapter 18 Notes – Electronics

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In this post, I am sharing the Class 12 Physics Chapter 18 Notes PDF for the students of Intermediate Part 2. This chapter’s name is Electronics. Students can download the Class 12 Physics Chapter 18 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 18 Notes – Electronics

Class 12 Physics Notes

#### Electronics

The branch of physics which deals with the motion of electrons (flow of current) through semiconductors is called electronics.

#### P-n Junction

The p-n junction is formed when a crystal of Germanium or silicon is grown in such a way that its half is doped with trivalent impurity and one half with pentavalent impurity. The p-n junction is an important building block of electronics.

#### How is transistor is used as a switch?

##### Transistor as a switch

The Collector C and emitter E behaves as terminals of switch. The circuit in which current is to be turned OFF and ON is connected across these terminals. The base B and emitter E act as control terminals which decide the state of the switch.

Working, In order to turn on the switch a large P.D Vb is applied between control terminals B.E. This inject a large current IB into base circuit due to which very large current Ic began to flow in C.E circuit. This value of large current is possible only when resistance between C and E drops to such a small value that the potential drops across C.E is nearly 0.1 volts. ammeter is at ground potential. So, we can suppose that collector is also at ground potential and C.E circuit can be drawn.