This question is about the velocity selector shown in figure.

State the directions of the magnetic and electric forces on a positively charged ion travelling towards the slit $S$.

This question is about the velocity selector shown in figure.

Calculate the speed of an ion emerging from the slit $S$ when the magnetic flux density is $0.30 T$ and the electric field strength is $1.5\times {10}^{3 }V{m}^{-1}.$

This question is about the velocity selector shown in figure.

Explain why ions travelling with a speed greater than your answer to part (b) will not emerge from the slit.

A Hall probe is designed to operate with a steady current of $0.020 A$ in a semiconductor slice of thickness $0.05 mm$. The number density of charge carriers (electrons) in the semiconductor is $1.5\times {10}^{23}{m}^{-3}$.

(a) Calculate the Hall voltage that will result when the probe is placed at right angles to a magnetic field of flux density $0.10 T$. (Elementary chargee$=1.60\times {10}^{-19}C.$)

A Hall probe is designed to operate with a steady current of $0.020 A$ in a semiconductor slice of thickness $0.05 mm$. The number density of charge carriers (electrons) in the semiconductor is $1.5\times {10}^{23}{m}^{-3}$.

(b) Explain why the current in the Hall probe must be maintained at a constant value.

A scientist is doing an experiment on a beam of electrons travelling at right angles to a uniform magnetic field of flux density $B$. The graph shows the variation of the magnetic force $F$ acting on an electron with the speed v of the electron.

The gradient of the graph is $G$. The magnitude of the charge on the electron is e. What is the correct relationship for the magnetic flux density $B$?

A $B=G$, B $B=G\times e$, C $B=\frac{G}{e}$, D $B=\frac{e}{G}$