The end of a cylindrical plastic rod is polished and cut perpendicular to the axis of the cylinder
Determine the minimum index of refraction so that a light ray entering the end of the rod will always be totally internally reflected within the rod, i.e., it will never escape the rod until it comes to the other end. Assume a critical angle of 45°.
1.414
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Methane should be rapidly destroyed in Titan's atmosphere, yet it is still present in appreciable amounts. How can this be?
A) on the surface of Titan live cows that are constantly producing methane gas B) larger hydrocarbons like ethane and propane are being broken down by ultraviolet light into methane C) methane may be continually evaporating from the surface and the interior D) comet impacts are constantly supplying the atmosphere with fresh methane
When a ferromagnetic material is placed in an external magnetic field, the net magnetic field of its magnetic domains becomes
A) smaller. B) zero. C) larger.
Consider what happens when you jump up in the air. Which of the following is the most accurate statement?
A) It is the upward force exerted by the ground that pushes you up, but this force can never exceed your weight. B) You are able to spring up because the earth exerts a force upward on you which is stronger than the downward force you exert on the earth. C) Since the ground is stationary, it cannot exert the upward force necessary to propel you into the air. Instead, it is the internal forces of your muscles acting on your body itself which propels the body into the air. D) When you push down on the earth with a force greater than your weight, the earth will push back with the same magnitude force and thus propel you into the air.
The major source of CO pollution is
a. combustion for electrical generation. b. industry. c. domestic heating. d. transportation.