State the de Broglie relation, explaining any symbols you use.
An electron of mass 
has kinetic energy 
. Show that the de Broglie wavelength 
of this electron is given by
Calculate the potential difference through which an electron, initially at rest, must be accelerated so that its de Broglie wavelength is equal to 
(the diameter of an atom).
is Planck's constant
is the momentum of the particle.
.
