BASIC ELECTRONICS SESSION-3 CLASSIFICATION OF SUBSTANCES BASED ON ENERGY BAND DIAGRAM BY ASIF ANSARI

CLASSIFICATION OF SUBSTANCES BASED ON ENERGY BAND DIAGRAM.
THERE ARE THREE SUBSTANCES
1) CONDUCTORS
2) INSULATORS
3) SEMI-CONDUCTORS
CONDUCTORS:
1) IN THIS FORBIDDEN ENERGY GAP (F E G) IS ZERO.
2) ELECTRONS CAN EASILY MOVE FROM VALENCE BAND (V.B) TO CONDUCTION BAND (C.B).
3) HENCE CURRENT CONDUCTION (FLOW OF CURRENT) IS MORE IN CONDUCTORS.
EXAMPLES : METALS SUCH COPPER ,ALUMINIUM etc.
INSULATORS:
1) FEG IS LARGE BETWEEN VALENCE BAND AND CONDUCTION BAND
(15 EV).
2) HENCE NO FLOW OF CURRENT IN INSULATOR BECAUSE NO FREE
ELECTRONS IN CONDUCTION BAND.
EXAMPLES : RUBBER ,PLASTIC etc
SEMI-CONDUCTORS:
1) THE FEG BETWEEN VALENCE BAND AND CONDUCTION IS SMALL (1 EV.)
2) THE CONDUCTIVITY OF SEMI-CONDUCTOR LIES BETWEEN CONDUCTORS AND INSULATORS.
3) THE CURRENT CONDUCTION(FLOW OF CURRENT) IN SEMI-CONDUCTOR IS MORE THAN INSULATORS BUT LESS THAN CONDUCTORS.
4) WHEN TEMPERATURE INCREASES SEMI CONDUCTORS ACTS AS CONDUCTORS.
5) WHEN TEMPERATURE DECREASES SEMI CONDUCTORS ACTS AS INSULATORS.
EXAMPLES : SILICON (SI ), GERMANIUM(GE)

#BASIC# ELECTRONICS# ENERGY# BAND#DIAGRAM,