Answer to Question 1
ANSWER: The corona is due to diffraction of lightthe bending of light as it passes around objects. To understand the corona, imagine water waves moving around a small stone in a pond. As the waves spread around the stone, the trough of one wave may meet the crest of another wave. This situation results in the waves canceling each other, thus producing calm water. (This is known as destructive interference.) Where two crests come together (constructive interference), they produce a much larger wave. The same thing happens when light passes around tiny cloud droplets. Where light waves constructively interfere, we see bright light; where destructive interference occurs, we see darkness.
Answer to Question 2
ANSWER: As you look at a rainbow, keep in mind that only one ray of light is able to enter your eye from each drop. Every time you move, whether it be up, down, or sideways, the rainbow moves with you. The reason why this happens is that, with every movement, light from different raindrops enters your eye. The bow you see is not exactly the same rainbow that the person standing next to you sees. In effect, each of us has a personal rainbow to ponder and enjoy
a pocket mouse, Perognathus sp., a small granivor
Why Cells Are Small 2
Pulse oximetry. The small device provides a digital readout of oxygen levels in the blood.
Map of the Moon by Johannes Hevelius from his Selenographia (1647), the first map to include the lib
The Moon’s Interior
For the circuit in Figure 1, assume ideal diodes. The peak inverse voltage is approximately