University:
University of California, San Diego
Course:
PHYS1a | Physics
Academic year:

2022
Views:

429

Pages:

3
Author:

Nitish Kumar

# DOUBLE-SLIT EXPERIMENT WITH ELECTRONS - Since electrons act as waves, we should expect a diffraction pattern if we allow them to pass through a double slit screen, assuming that the size of the slit is on the order of the wavelength of the wave. Intensity of fringes formed on the screen by the electrons Double slit viewing screen As we saw in Young's experiment, light forms an interference pattern that is visible to the eye. Although electrons form a similar pattern, the pattern must be visualized using a fluorescent screen. But what happens if we decrease the number of electrons that pass through the openings to the point where only one electron enters the slit at any given time. At first, the location of where electrons hit the screen would appear to be completely arbitrary. However, if we allow the experiment to run for a very long time, a pattern will emerge. (1) Initially (2) After long time Although it would be impossible to predict where each individual electron would strike the screen, we could in fact predict the probability of an electron striking a certain region of screen. This probability is given by |ψ|², the square of the wave function. Inside the dark fringes, the |ψ|² is a very small value (≈0) while in regions where bright fringes are formed the |ψ|² is a large value. Conclusion - ① A diffraction pattern is only produced when wave interference takes place. Since only a single electron travels through any one slit at any given time, this implies that the electron must travel through both openings at the some time to produce wave interference; this only happens if electrons act as a wave. ② For waves ψ measures displacement; for particles it measures probability.