111
qn
R
H
1
=
(3)
where q is the charge.
From Equation (3), it is clear that the sign of charge carrier and
density can
be estimated
from the
sign
and value of Hall coefficient R
H
.
R
H
can be obtained by studying variation
of V
H
as a function of I for given B.
Experimental Setup
Sample is mounted on a sunmica sheet with four spring type pressure contacts. A
pair of green colour leads are provided for current and that of red colour for hall voltage
measurement. Note the
direction of current
and voltage measurement carefully.
Do not
exceed current beyond 10 mA
.
The unit marked "Hall Effect Setup" consists of a constant current generator
(CCG) for supplying current to the sample and a digital milli voltmeter to measure the
Hall voltage. The unit has a digital display used for both current and Hall voltage
measurement.
For applying the magnetic field an electromagnet with a constant current supply is
provided. It is capable of generating a magnetic field of 7.5 Kgauss between its pole
pieces. The magnetic field can be measured by gauss meter along with the hall probe
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 Fall '09
 LIND
 Magnetic Field, Hall voltage

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