= Hall effect
{c}
{wiki}
The voltage changes perpendicular to the current when magnetic field is applied.
\Image[https://upload.wikimedia.org/wikipedia/commons/1/19/Hall_Effect_Measurement_Setup_for_Electrons.png]
{title=<Hall effect> experimental diagram}
{description=The <Hall effect> refers to the produced voltage $V_H$, AKA $V_y$ on this setup.}
An intuitive video is:
\Video[https://upload.wikimedia.org/wikipedia/commons/transcoded/7/77/Hall_Sensor.webm/Hall_Sensor.webm.480p.vp9.webm]
The key formula for it is:
$$
V_{H} = \frac{I_x B_z}{n t e}
$$
where:
* $I_x$: current on x direction, which we can control by changing the voltage $V_x$
* $B_z$: strength of transversal <magnetic field> applied
* $n$: <charge carrier density>, a property of the material used
* $t$: height of the plate
* $e$: <electron charge>
Applications:
* the direction of the effect proves that electric currents in common electrical conductors are made up of negative charged particles
* <magnetometer>[measure magnetic fields], TODO vs other methods
Other more precise non-classical versions:
* <quantum Hall effect>{child}
Bibliography:
* http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/Hall.html