The document provides an overview of electrical materials, categorizing them as conductors, insulators, semiconductors, and photoconductors. It explains the characteristics, applications, and differences between these materials, detailing how conductors allow electricity to flow while insulators hinder it. Additionally, the document discusses energy band theory and the reasons for the differing conductive properties of metals and plastics.

1. CREATOR:- AYUSH BHARDWAJ (07)
SOCIAL NAME:- ABIVILION
REG NO:-11901812
COURSE CODE :- PHY109
SCHOOL : - COMPUTER SCIENCE &
ENGINEERING

2. TABLE OF CONTENTS
• Introduction
• Conductors
• Insulators/Plastics/Semiconductors
• Photoconductors
• Energy Band (Diagram)
• Why metal conducts and plastics don’t?
2

3. INTRODUCTION
Nature of materials meant by characteristics, qualities, complexions and inherent features
of materials. On the basis of different or semi-different essence of the materials are
compared certain numerous criteria's such as crystalline structure, molecular structure,
M.P.T, B.P.T, mass of materials etc.
3

4. CONDUCTORS
Conductors are the materials or substances which allow electricity to flow through them.
They are able to conduct electricity because they allow electrons to flow inside them very
easily. Conductors have this property of allowing the transition of heat or light from one
source to another.
Metals, humans, earth, and animal bodies are all conductors. This is the reason we get
electric shocks! The main reason is that being a good conductor, our human body allows
a resistance-free path for the current to flow from wire to our body.
Conductors have free electrons on its surface which allows current to pass through. This is
the reason why conductors are able to conduct electricity.
EXAMPLES OF CONDUCTORS :-Silver Copper, Aluminum, etc.
Gases are not good conductors of electricity.
4

5. INSULATORS/PLASTICS
Insulators possess a high resistivity and low conductivity. Their atoms have tightly bound
electrons that do not move throughout the material. Because the electrons are static and not
freely roaming, a current cannot easily pass. In addition to protecting loss of current,
insulators make an electrical current more efficient by concentrating the flow.
EXAMPLES OF INSULATORS :- Rubber, Glass, Pure water, etc.
PLASTICS
Plastics are typically organic polymers of high molecular mass and often contain other
substances. They are usually synthetic, most commonly derived from petrochemicals,
however, an array of variants are made from renewable materials such as polylactic acid
from corn or cellulosic from cotton linters.
EXAMPLES OF PLASTICS :- Polyethylene Terephthalate, HDPE, PVC, LDPE
5

6. 6

7. SEMICONDUCTORS
Semiconductor, any of a class of crystalline solids intermediate in electrical conductivity
between a conductor and an insulator. Semiconductors are employed in the
manufacture of various kinds of electronic devices, including diodes, transistors,
and integrated circuits. Such devices have found wide application because of their
compactness, reliability, power efficiency, and low cost. As discrete components, they
have found use in power devices, optical sensors, and light emitters, including solid-
state lasers. They have a wide range of current- and voltage-handling capabilities and,
more important, lend themselves to integration into complex but readily manufactural
microelectronic circuits
7

9. PHOTOCONDUCTORS
Photoconductivity is an optical and electrical phenomenon in which a material becomes
more electrically conductive due to the absorption of electromagnetic radiation such as
visible light, ultraviolet light, infrared light, or gamma radiation. When light is absorbed by a
material such as a semiconductor, the number of free electrons and electron holes increases
and raises its electrical conductivity. To cause excitation, the light that strikes the
semiconductor must have enough energy to raise electrons across the band gap, or to excite
the impurities within the band gap. When a bias voltage and a load resistor are used in
series with the semiconductor, a voltage drop across the load resistors can be measured
when the change in electrical conductivity of the material varies the current flowing through
the circuit.
EXAMPLES:-polyvinylcarbazole, lead sulphide,
and selenium.
9

10. APPLICATIONS OF PHOTOCONDUCTORS
When a photoconductive material is connected as part of a circuit, it functions as
a resistor whose resistance depends on the light intensity. In this context, the material is
called a photoresistor (also called light-dependent resistor or photoconductor). The most
common application of photoresistors is as photodetectors, i.e. devices that measure light
intensity. Photoresistors are not the only type of photodetector—other types
include charge-coupled devices (CCDs), photodiodes and phototransistors—but they are
among the most common. Some photodetector applications in which photoresistors are
often used include camera light meters, street lights, clock radios, infrared detectors,
nanophotonic systems and low-dimensional photo-sensors devices.
10

11. ENERGY BANDS
An energy band is a range of electron energy in a solid so dense with electron states that it
appears to be continuous. The number of states is finite and countable but the spacing
in energy between states is miniscule. The number of discrete states in a band is on the
order of the number of electrons in the solid.
ENERGY BAND THEORY
According to Bohr's theory, each and every shell and subshell of atoms contain a discrete
amount of energy. When atoms are brought closer to each other, electrons at outermost
shell interact with each other. This bonding force between electrons is called as an inter-
atomic interaction.
11

13. WHY METALS CONDUCTS AND PLASTICS DON’T?
• Metals are good conductors of electricity because they contain free electrons.
Insulators such as plastic and rubber do not generally contain free electrons and so
are poor conductors of electricity.
• Metals having very less resistance and on other side Plastics having very resistance
for electricity conduction.
13

14. THANK YOU !
14