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Hall Effect
Principle of the experiment:
If an electric current flows through a conductor in a magnetic field, the magnetic field
exerts a transverse force on the moving charge carriers, which tends to push them to
one side of the conductor. This is most evident in a thin flat conductor as illustrated. A
build up of charge at the sides of the conductors will balance this magnetic influence,
producing a measurable voltage between the two sides of the conductor. The presence
of this measurable transverse voltage is called the Hall effect after E. H. Hall who
discovered it in 1879.
The aim of the manipulation: Transport property
investigations
The Hall effect is a conduction phenomenon, which is different for different charge
carriers. In most common electrical applications, the conventional current is used
partly because it makes no difference whether you consider positive or negative
charge to be moving. But the Hall voltage has a different polarity for positive and
negative charge carriers, and it has been used to study the details of conduction in
semiconductors and other materials which show a combination of negative and
positive charge carriers.
The Hall effect can be used to measure the average drift velocity of the charge carriers
by mechanically moving the Hall probe at different speeds until the Hall voltage
disappears, showing that the charge carriers are now not moving with respect to the
magnetic field (not to be considered here).
Experimental details:
You have at your disposal a coil with iron core for the generation the magnetic field, a
current source witch generate the flow of the carrier and a voltmeter that will measure
the so cold Hall voltage.
Theory:
1- Explain precisely how a flow of charged particle interacts with a perpendicular
magnetic field.
2- Explain, according to the illustration above, why a voltage builts up and quantify it
3- Calculate the magnetic filed generated by an iron core solenoid.
4- How can we classify and differentiate material regarding their electrical behaviour.
Discuss in few sentences what is a semiconductor and a doped semiconductor.
Experiment:
Deduce from the measurement the type of the material under investigation.