A beam of identical positive ions travels horizontally in a vacuum. The ions pass
between two charged plates and are deflected downwards by the electric field between
The diagram shows the path of one of the ions.
Explain the path of the ion both between the plates and when it has left the plates.
Whilst the electric field is still acting, the path of the ions can be returned to the
horizontal by applying a magnetic field over the same region as the electric field acts.
Explain the conditions under which the ions have no overall deflection as they
pass between the plates.
potential difference across the plates is 60 V.
Calculate the magnetic flux density required so that there is no overall deflection
of the ions.
Magnetic flux density =
State and explain how the path of the ions in just the magnetic field would be
different from the path in just the electric field.