Explain arrangement of Davission and Germer experiment.

Explanation

The wave nature of electron was first experimentally verified by C.J. Davission and L.H. Germer in 1927 and G.P.Thomson in 1928.
Davisson and Thomson shared Nobel Prize in 1937 for their experimental discovery of diffraction of electron by crystals.
Experimental arrangement:Figure shows schematic arrangement of Davisson and Germer experiment.
It consist of an electron gun which comprises of tungsten filament F,coated with barium oxide and heated by a low voltage power supply (L.T. battery)filament is heated by passing current through L.T. Battery.
When filament is heated due to thermionic emission electrons are emitted which are accelerated by H.T. battery to a desired velocity.
Thses electrons are made to pass through a cylinder with fine holes along axis producing a fine collimated beam.The beam is made to fall on the surface of the crystal.
Electrons are scattered in all directions by atoms of crystal .
THe intensity of electron beam scattered in given direction is measured by electron detector (collector).
The detector can be moved on a circular scale and it is connected with sensitive galvanometer which records currents.
The deflection of the galvanometer is proportionl to the intensity of the electron beam entering the collector.
The apparatus is enclosed in an evacuated chamber.