Experiment 4- Diffraction And Interference Flashcards
How can laser light be characterized? What does this mean?
It can be characterized as monochromatic, meaning that THERE’S A SINGLE WAVELENGTH PRESENT.
How can packets of waves be characterized? Define them.
As either coherent or incoherent. Incoherent: various wavelengths, directions, and phases with respect to each other.
Coherent: light traveling in the same direction with the same wavelength and phase.
Define Coherent
Laser light propagates as a single train of waves that extend uniformly over the cross section of the laser beam.
Define Incoherent
Propagation via a large number of short trains of waves randomly arranged with respect to another.
What happens when coherent light passes through an opening?
We get alternating bright and dark spots on the screen that can be attributed to the path length difference between the two light waves.
What is the formula for the path-length difference between the two light waves?
Mlambda.
For our purposes, how will the width of each slit and the distance between the CENTER OF TWO SLITS BE DENOTED?
A IS THE WIDTH of each slit and D is the distance between the center of two slits.
For points of observation far from the screen, _____ will occur. What requirement has to be present for this to happen?
Intensity Maxima; difference in distance should be an integer number of wavelengths. Dsintheta=mlambda
What is the relationship between the number of slits and the sharpness of maxima?
Direct. The more slits there are, the sharper the maxima intensity.
For our purposes, what does m denote?
The integer number of wavelengths of path length difference originating from both slits.
What is the equation for the small angle approximation that will be used? What is the caveat?
Sin Theta= y/(L^2+y^2)^1/2, where y is the distance between the interference maxima, L is the distance between the slit and the screen. Since the angle is so small, we can approximate: sin theta= y/L
Combining the small angle approximation with the single-slit diffraction first minus distance gives what equation?
Y=LambdaL/a
