A thin slice of conducting material has its faces PQRS and VWXY normal to a uniform magnetic field of flux density B, as shown in the figure below.
Electrons enter the slice at right-angles to face SRXY. A potential difference, the Hall voltage 
, is developed between two faces of the slice.
Use letters from the figure above to name the two faces between which the Hall voltage is developed.
State and explain which of the two faces named in (a)(i) is the more positive.
The Hall voltage is given by the expression
Use the letters in the figure above to identify the distance 
.
State the meaning of the symbol 
.
State and explain the effect, if any, on the polarity of the Hall voltage when negative charge carriers (electrons) are replaced with positive charge carriers, moving in the same direction towards the slice.
