Hall effects state that : " if a specimen ( metal or semiconductor ) carrying the current I is placed in transverse magnetic field B , an electric field intensity E is induced in a direction perpendicular to both I and B" .
Where w is the width of specimen d is the height or thickness of the specimen (or) spacing between bottom surface and under surface of specimen.
• Representation of hall voltage :
symbol : Metal or N - type sc
Symbol: p-type sc
App
•Application:
•Hall effect is used to find whether a semiconductor is n type or semiconductor
•Hall effect is used to find carrier concentration mobile and conductivity.
•Hall effect is used to measure strength of magnetic field.
•Hall effect is used in an instrument called hall effect multiplier.
• Key points :
1. VH = B.I / ρ.w where ρ = charge density
B = magnetic field
I =magnetic current
w = thickness
2. Charge density ( ρ ) = charge × carrier concentration
3.Hall coefficient : RH = 1 / ρ
4. VH = RH.B.I /w
=) VH ∝ RH. Where B.i /w = constant
If VH or RH =) - ve then n- type , metal , intrinsic s.c
If VH or RH =) +ve then p- type.
Note : Metal > n- type > intrinsic s.c
5. Hall voltage (VH ) is directly proportional to magnetic field and current while
Hall voltage is also inversely proportional to mobile charge carrier and thickness.
