Mention some applications of velocity selector.

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.

Explain how crossed $\overrightarrow{E}$ and $\overrightarrow{B}$ fields serve as a velocity selector.

A parallel plate capacitor made of circular plates each of radius $R=6.0 \mathrm{cm}$ has a capacitance $\mathrm{C}=100 \mathrm{p}\mathrm{F}.$ The capacitor is connected to a $230 \mathrm{V}$ ac supply with an (angular) frequency of $300\text{\hspace{0.17em}rad\hspace{0.17em}}{\text{s}}^{\text{-1}}$. Determine the amplitude of $\mathrm{B}$ at a point $3.0 \mathrm{cm}$ from the axis between the plates.