Transcript Diffraction by a Disk

1. Would yellow light or green light produce the wider twoslit interference pattern?
2. If light and sound are both wave phenomena, why can we
hear sounds around a corner but cannot see around a
corner?
3. Red light is used to form a two-slit interference pattern on
a screen. As the two slits are moved farther apart, does the
separation of the bright bands on the screen decrease,
increase, or remain the same?
Diffraction by a Disk
Diffraction by a Single Slit
Conceptual Example:
Light shines through a rectangular hole
that is narrower in the vertical direction
than the horizontal.
Would you expect the light to diffract
more in the vertical direction or in
horizontal direction?
Diffraction Grating
A large number of equally spaced
parallel slits is called a diffraction
grating.
Why more slits yield sharper peaks?
The bright maxima are much sharper and
narrower for grating.
Spectra Produced by a Grating
The Spectrometer and
Spectroscopy
Limits of Resolution
The ability of lens to produce distinct images
of two point objects very close together is
called the resolution of lens.
The two images are just resolvable when the
center of the diffraction disk of one is directly
over the first minimum in the diffraction
pattern of the other.
1. Why can’t an ordinary microscope using visible light be
used to observe individual molecules?
2. Is it better to use red light or blue light to minimize
diffraction effects while photographing tiny objects through
a microscope? Why?
3. Why are the diffraction effects of your eyes more important
during the day than at night?
Interference by Thin Film
A beam of light reflected by a material
whose index of refraction is greater than
that of the material in which it is traveling,
changes phase by ½ cycle.
Polarization
1. Can sound waves be polarized?
2. If all the labels had come off the sunglasses
in the drug store, how could you tell which
ones were polarized?
Holography