Principle

Fast electrons are diffracted from a polycrystalline layer of
graphite: interference rings appear on a fluorescent screen. The
interplanar spacing in graphite is determined from the diameter of
the rings and the accelerating voltage.

Tasks


To measure the diameter of the two smallest diffraction rings
at different anode voltages.

To calculate the wavelength of the electrons from the anode
voltages.

To determine the interplanar spacing of graphite from the
relationship between the radius of the diffraction rings and the
wavelength.


What you can learn about


Bragg reflection

Debye-Scherrer method

Lattice planes

Graphite structure

Material waves

De Broglie equation