Time, Space and Light. Visible Light makes up such a small part of the spectrum, but there is still so much mystery and wonder about it all.
Question: Is a radio wave also a sound wave?
Answer: No, radio waves are part of the Electromagnetic Spectrum and sound waves are mechanical productions of air being pushed.
What is light? Technically, we don’t know. But we have some really fine theories that work well mathematically to give us close approximations.
Light is energy carried in an electromagnetic wave that emanates from vibrating electrons in atoms.
Visible light vibrates at a very high rate, some 100 trillion times per second (1014 Hertz). Light has an approximate speed of 300,000 km/s or 186,000 miles/sec.
UV light is responsible for sunburns due to its high frequency and clouds are semi-transparent to UV that is how you get burnt on a cloudy day.
Question: Why are lunar eclipses more commonly seen then solar eclipses?
Answer: The shadow of the relatively small moon on the large earth covers a very small part of the earth’s surface. Only a relatively few people are in shadow of the moon in a solar eclipse. But the shadow of the earth completely covers the moon during a total lunar eclipse so everybody who views the nighttime sky can see the shadow of the earth on the moon.
Light enters the human eye through the transparent cover called the cornea, which does about 70% of the necessary bending of light before it passes through the pupil. The light then passes through the lens, which is used only to provide the extra bending power needed to focus images of nearby objects on the layer at the back of the eye. There is also a spot in the retina where all the nerves carrying all the information exit; this is the blind spot.
The size of your pupils depends on your mood. Poker players have unwittingly given themselves away when they had a good hand by the size of their pupils!
Why is the sky blue?
A beam of light falls on an atom and causes the electrons in the atom to vibrate. The vibrating electrons, in turn, re-emit light in various directions. Light is scattered. This is known as Rayleigh Scattering. The shorter the wavelength of light the more light is scattered.
Why are sunsets red?
The lower frequencies of light are scattered the least by nitrogen and oxygen molecules, the primary component of our atmosphere. Therefore red, orange, and yellow light are transmitted through the atmosphere much more than violet or blue. Red, which is scattered the least, passes through more atmosphere than any other color.
Reflection and Refraction
Light interacts with atoms as sound interacts with tuning forks.
The Principle of Least Time – stated in 1650 by Pierre Fermat, Out of all possible paths that light might take to get from one point to another, it takes the path that requires the shortest time.
Index of refraction (n) = speed of light in vacuum divided by the speed of light in material
2 comments:
Today we discussed how a CD works. How Stuff Works has the best explanation I've ever seen on how it all works, even REwritable CD's.
Josh,
Thanks for the excellent reference!
It was a fun place to visit.
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