Conceptual Questions Chap. 13

Download Report

Transcript Conceptual Questions Chap. 13

Conceptual Questions Chap. 22
1.
Why does the arc of a rainbow appear with red on top and violet on the
bottom?
The spectrum of the light sent back to you from a drop at the top of the rainbow arrives
such that the red light strikes the eye while the violet light passes over your head. At
the bottom of the bow, violet light arrives at your eye and red light is deviated toward
the ground (see Figure 22.20).
2.
Under what conditions is a mirage formed? On a hot day, what are we seeing
when we observe a mirage water puddle on the road?
A mirage occurs when light changes direction as it moves between batches of air
having different indices of refraction, due to air having different densities at different
temperatures. Two images are seen: one from a direct path from the object to you,
and the second arriving by rays originally heading toward the ground but refracted to
your eye. On a hot day, the Sun makes the surface of blacktop hot, so the air is hot
directly above it, becoming cooler with increasing altitude. The “water” we see is an
image of the blue sky. Shimmering occurs when the air changes in temperature.
3.
The level of water in a clear, colorless glass is easily observed with the naked
eye. The level of liquid helium (which has an index of refraction close to that of
air) in a clear glass vessel is extremely difficult to see with the naked eye.
Explain.
The index of refraction of water is quite different from air, while the index of refraction
of liquid helium happens to be much closer to that of air. Consequently, light
undergoes less refraction at the helium-air interface than it does at the water-air one.
4.
Why does a diamond show flashes of color when observed under white light?
The diamond acts like a prism in dispersing the light into its spectral components.