A thin rectangular slice of aluminium has sides of length 
, 
and 
, as shown in the figure below.
Some of the corners of the slice are labelled. A current 
of 
is normal to face RSXY of the slice. In aluminium, the number of free electrons per unit volume is 
. A uniform magnetic field of magnetic flux density 
equal to 
is normal to face QRYZ of the aluminium slice in the direction from Q to P. A Hall voltage 
is developed across the slice and is given by the expression
Use the figure above to state the magnitude of the distance 
.
Calculate the magnitude of the Hall voltage .
.
