The document discusses PN-junction diodes and their general applications. It begins by explaining that a diode is formed by placing a P-type and N-type semiconductor together, forming a PN junction. Electrons diffuse from the N to P side and holes diffuse from the P to N side, creating a depletion region. This process stops when an electric field is produced that opposes further diffusion. General applications of diodes include using them in half-wave and full-wave rectifier circuits to convert AC to DC, and filter circuits to remove AC components from the rectified output. Diodes also find use as LEDs, in transistors, and have many other applications like switching, amplifying and oscillating.

1. PHYSICS PRESENTATION.
PN-junction Diode
&
General Applications of Diode
By Bhavin Gupta
EE-F1
Enroll.no 130120109011

2. PN-JUNCTION DIODE
 Diode is a electronic component , generally used as a switch, as LED, as
a rectifier to convert A.C current to D.C current, as a transistor & in
various other circuits.
 It can be represented in a circuit diagram as : -

3. A diode is formed by placing two semi conductors
together one of N-type & another of P-type .
• P-N junctions are formed by joining n-type and p-
type semiconductor materials.
P-type semiconductor have holes as
majority charge carrier. Due to trivalent
impurity(Aluminium: Al)
N-type semiconductor have electrons as
majority charge carrier. Due to
pentavalent impurity.(Arsenic: As)

4. As shown in figure P-type
semiconductors is brought
nearer to N-type semiconductors.
Electrons starts to defuse
gradually from N section to P
section .
Similarly holes defuses from P section to
N section.
 Due to which a depletion region is formed at the
junction.

5.  As electron from impurity of N
section is defused to the impurities of
P section & vice versa, the Al
atoms becomes negative ion and
As atom become positive ion near
Junction forming depletion layer
 As the diffusion process continues
the +ve & -ve charge increases respectively.
 Due to this an Electric field is also produced which now opposes the flow of
electrons and holes.
 The process of diffusion stops when sufficient electric field is produced.
 This is how a PN junction diode is formed.

6. GENERAL APPLICATIONS OF DIODE
 Half wave rectifier
 Full wave rectifier
 Filter circuit

7. HALF-WAVE RECTIFIERS
This circuit converts one
ac cycle to a DC output.
Full-wave Rectifiers
This circuit converts both
AC input cycles to DC
output.
Filter cuircuit
The DC-output provided by Full wave
and half wave rectified circuit contains
AC component also.
To remove this AC component Filter
circuit is used.

8. OTHER APPLICATIONS OF DIODE
LED(Light emitting diode)
NPN/PNP Transistor
Rectifiers
Transistor is further having wide range of uses:
As a switch, Amplifier & oscillator also.

9. Thank You