1)The P ray is directed parallel to the axis of the lens. It emerges from the lens directed toward the focal point on the side of the lens opposite the object.
2) The M ray is directed toward the midpoint of the lens. It emerges from the lens unchanged in direction.
3) The F ray is directed toward the focal point on the same side of the lens as the object. It emerges from the lens directed parallel to the lens axis.
Answer:
The absorption lines will shift to the red (become longer).
This is because of the extra distance that a wavelength λ must travel between the vibrations of the source producing the spectrum.
Note that the Doppler effect of the source is slightly different for light waves than it is for sound waves because sound waves require a medium in which to travel while light waves do not require such a medium (example air).
The line in which waves that are moving together are all in the same phase is referred to as the wave front.
For example, in a series of waves, all of the crests that are in a single line make up a single wave front. This is the case for every set of particles at the same specific point in a series of waves.