16.7 Hall Effect
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Chapter 16 16.7 Hall Effect
Transcript of 16.7 Hall Effect
Chapter 16
16.7 Hall Effect
16.7 Hall Effect
*Textbook pg 228 Figure 16.44
16.7 Hall Effect
When a magnetic field B is applied perpendicular to the current, there is a magnetic force acting on each conducting electron. The direction of the magnetic field on the electron can be determined by using Fleming’s Left Hand Rule.
16.7 Hall Effect
The direction of the magnetic force is upward. This force pulls the electrons towards the upper surface.
16.7 Hall Effect
As a result, the upper surface will have a higher concentration of electrons. Hence, a potential difference (perpendicular to B and I) is produced.
16.7 Hall Effect
The potential difference is called “Hall voltage (VH)” and the effect is called the “Hall Effect”.
16.7 Hall Effect
“Hall Effect” is the phenomenon that occurs in a conductor carrying a current when it is placed in a magnetic field perpendicular to the current. The charge carriers in the conductor become deflected by the magnetic field and give rise to an electric field (Hall field) that is perpendicular to the both current and magnetic field.
16.7 Hall Effect
16.7 Hall Effect
As the charges accumulate on opposite edges of the conductor, the strength of the electric field increases, so does the electric force on the charge carriers.
16.7 Hall Effect
The electric field produces an electric force on each drifting free electron in the conductor.
Electron force on an electron = EHall(e)
16.7 Hall Effect
When a Hall voltage (VH) is present in a conductor, every electron is subjected to two forces, the magnetic force(upward) and the electric force(downward), they are equal and opposite.
16.7 Hall Effect
Hall effect for positive charge carriers (left) and negative charge carriers (right).
16.7 Hall Effect
The separation of the charges stops when the magnitude of the electric force equals to the magnitude of the magnetic force
FE=FM
16.7 Hall Effect
dvBV
qvBdV
q
qvBqEFF
H
H
ME
16.7 Hall EffectCurrent, I, is related to the drift velocity, v, the number of charge carries per unit volume n and the cross-sectional area A of the conductor by the expression
nAeIv
nAveI
16.7 Hall Effect
conductor theof thickness* surfacelower andupper between distance*
*
td
netBIV
tdABnAeI
dV
vBEqvBqEFF
H
H
ME
16.7 Hall EffectHall voltage in different conductors can
be positive, negative or zero.
WHY?1.Positive Hall voltage – the majority of the
charge carriers are positively charged.2.Negative Hall voltage – the majority of the
charge carriers are negatively charged or free electrons.(the polarity of the Hall voltage reversed)
3.Zero Hall voltage – there are equal numbers of positive and negative charge carriers in the conductor.
