Calculate the de broglie wavelength of an electron that has been acceleraed from rest through a potential differnece of 1kV.
The kinetic energy of the electron is there 1000 electron-volt (E = Q*V)
Since the electron mass is known, what is the momentum that corresponds to 1000 electron-volt kinetic energy?
you should be able to calculate the wavelength from the momentum using debroglie's equation.