Edwin H. Hall, an American physicist in the 19th century, discovered the Hall effect which allows for the measurement of magnetic fields. The Hall effect occurs when a conductor carrying an electric current is placed in a magnetic field perpendicular to the current. This interaction produces a potential difference on the sides of the conductor. Applications of the Hall effect include sensors used in doors, cars, computers, and anemometers. The document then discusses how Hall sensors can detect the polarity and strength of magnetic fields and how they are used to build circuits to detect magnet polarity. It also describes how mobile phone apps use Hall sensors to measure the Earth's magnetic field.

1. The Hall effect
Gruppo: Cristiano Franceschilli, Lorenzo Piccari, Stefano Ranalli, Anastasia Sagazio, Agnese Triozzi.
A.S. 2020/2021
Classe 5^C

2. Edwin H. Hall
Edwin H. Hall was an American
physicist, (1855-1938), before
him it was very complex to
measure the magnetic field, but
thanks to his very ingenious
studies this was no longer
difficult, thanks to some
sensors.
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3. What is Hall Effect?
For the Hall Effect there’s an interaction between .
Semi-conducting /
conducting metal
Magnetic field
The interaction creates a potential difference on
the two plates
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4. Hall effect explained
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.
The Hall voltage is given by:
VH = IB/ned
n = density of mobile charges
e = electron charge.
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5. Hall voltage for positive charges
Through the hall effect it is possible to understand whether the moving charges in
a conductor are positive or negative.
if the charge carrier is
positive, positive
charge will be on the
upper part of the
foil.The other way
around for negative
charges
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6. Applications of the Hall effect
The main application of the Hall effect is the Hall sensor which can be used with:
-door;
-car (wheel rotation sensor);
-computer;
-anemometers.
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7. Hall sensor V S reed switches
- The reed switches can be
inserted into a larger circuit
- they are mechanical and
have moving part
-they can not detect the strength
of magnetism because they are
on or off
-The hall effect sensor can be
inserted into a larger circuit
-they are electronic and have no
moving parts
-they can detect the strength of
magnetism.
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8. How to make a magnet polarity detection circuit
Using:
● a computer cooling fan,
● LEDs,
● a resistor,
● breadboard,
● a DC power supply.
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9. How to make a magnet polarity detection circuit
● the magnet is orientated with its
positive pole near the Hall sensor;
● the blue LED lights up.
● the magnet is orientated with its
negative pole near the Hall sensor;
● the green LED lights up.
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10. We could use a geomagnetometer that use
an axial probe or a tangential probe.
How is it possible to measure Earth's magnetism?
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11. How is it possible to measure
Earth's magnetism?
Apps on our
phones can also
be used to detect
a magnetic field.
For example the
compass app,
this one works
through three
Hall sensors.
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12. About how we made the powerpoint
for the creation of thi Powerpoint
the following link have been used:
● hyperphysics.phy-astr.gsu.edu
● www.explainthatstuff.com
● www.wired.com
we students work online using :
● google drive
● google presentazioni