For the free electrons moving in the slice, state the direction of the force on an electron caused by its motion in the magnetic field.
Using the letters on Fig. 8.1, identify the faces between which a potential difference is formed.
Explain why the potential difference in (a)(ii) reaches its largest value.
The density of free electrons in the material slice is $1.3 \times 10^{29}\,\text{m}^{-3}$. The slice thickness $PQ$ is $0.10\,\text{mm}$. The magnetic flux density $B$ is $4.6 \times 10^{-3}\,\text{T}$. Calculate the potential difference across the slice when the current is $6.3 \times 10^{-4}\,\text{A}$.
The slice in (c) is a metal. Using your answer in (c), suggest why Hall probes are generally made from semiconductors rather than metals.