Next: Electromagnetic Radiation.
Up: lect_notes
Previous: Waves in an arbitrary
Contents
What is light, particle or wave? Much of our daily experience with
light, particularly the fact that light rays move in straight lines
tells us that we can think of light as a stream of particles.
This is further borne out when place an opaque object in the path
of the light rays. The shadow, as shown in Figure 7.1 is a
projected image of the object, which is what we expect if light were a
stream of particles. But a closer look at the edges of the
shadow reveals a very fine pattern of dark and bright bands or
fringes. Such a pattern can also be seen if we stretch out our hand
and look at the sky through a thin gap produced by bringing two of our fingers
close.
This cannot be explained unless we accept that light is
some kind of a wave.
It is now well known that light is an electromagnetic wave. We shall
next discuss what we mean by an electromagnetic wave or
radiation.
Figure 7.1:
 |
Subsections
Next: Electromagnetic Radiation.
Up: lect_notes
Previous: Waves in an arbitrary
Contents
Physics 1st Year
2009-01-06