Which of the following kinds of signal do we currently have the best chance of detecting with currently technology?
A) a signal used for communication between a civilization's home world and another star system
B) a signal used for communication between a civilization's home world and another planet in its own planetary system
C) an intentional signal beacon
D) a signal used for local communication in the world where the intelligent beings exist
C
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Which forms of light are lower in energy and frequency than the light that our eyes can see?
A) infrared and radio B) ultraviolet and x-rays C) visible light D) infrared and ultraviolet
What centripetal acceleration is required to follow a circular path with a radius of 50 m at a speed of 20 m/s?
a. 6 m/s² b. 2 m/s² c. 8 m/s² d. 4 m/s²
In optical fibers of uniform density, light actually
A) curves in a direction parallel to the central axis of the fiber. B) travels in straight-line segments. C) travels along the outer surface of the fiber. D) none of the above
The pitch of a sound is determined primarily by its
A. duration. B. amplitude. C. speed. D. frequency.