130_notes.dvi

(Frankie) #1

No matter what distance between the slits we choose, wenever observe diffractionfor the bullets.
They always give theP 1 +P 2 pattern (probably different for the bullets).Can you explain this?
The bullet’s wavelength is much much smaller than the actual size of the bullet.


Why didn’t we see diffraction for the bullets. Bullets aremacroscopic objectswith huge momenta
compared to individual particles. High momentum implies a small deBroglie wavelength. So to see
diffraction, we must make the distance between the slits much smallerthan we did for the photons
(perhaps 10^20 times smaller). But bullets are also big. They only fit through big slits which
must them be further apart than the slits used for photons. For bullets,the wavelength is tiny
compared to any slit a bullet would fit through. Therefore no bullet diffraction is possible.


Feynman Lectures on Physics, Vol. III Chapter 1


3.6 Examples


3.6.1 Intensity Distribution for Two Slit Diffraction*


Derive the location of the nodes in the diffraction pattern from two narrow slits a distancedapart.
Now try to compute the intensity distribution.


This is an in lab exercise.


3.6.2 Intensity Distribution for Single Slit Diffraction*.


Derive the location of the nodes in the diffraction pattern from one slit of widtha. Now try to
compute the intensity distribution for single slit diffraction.


This is an in lab exercise.

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