Friday, May 28, 2010

The dual nature of the electron

Wave-Particle Duality/The Two-Slit Experiment/Electrons:
According to classical physics, electrons should behave like particles - the travel in straight lines and do not curve in flight unless acted on by an external agent, like a magnetic field. In this model, if we fire a beam of electrons through a double slit onto a detector, we should get two bands of "hits", much as you would get if you fired a machine gun at the side of a house with two windows - you would get two areas of bullet-marked wall inside, and the rest would be intact.

This was the behaviour noted . However, if the slits are made small enough and close enough together, we actually observe the following:

This means that the electrons are:
(1) Diffracting through the slits
(2) Interfering with each other just like waves.
This means that the electrons have wave-particle duality, just like photons.
In this case, they must have properties like wavelegngth and frequency. We can deduce the properties from the behaviour of the electrons as they pass through our diffraction grating.

s is the fringe spacing
λ is the wavelength
L is the distance from slits to screen
d is the grating spacing


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