Problem 6.211

In Hall effect measurements a plate of width $h=10 \mathrm{~mm}$ and length $l=50 \mathrm{~mm}$ made of $p$ -type semiconductor was placed in a magnetic field with induction $B=5.0 \mathrm{kG}$. A potential difference $V=10 \mathrm{~V}$ was applied across the edges of the plate. In this case the Hall field is $V_{H}=50 \mathrm{mV}$ and resistivity $\rho=2.5 \Omega \cdot \mathrm{cm}$ Find the concentration of holes and hole mobility.