Which of the following is an example of convection?
A) warm air expanding and rising, while cooler air contracts and falls
B) different kinds of material separating by density, like oil and water
C) rocks sinking in water
D) gas bubbling upward through a liquid
A) warm air expanding and rising, while cooler air contracts and falls
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Fiber optic cable is in the form of a cylinder of fiber with index of refraction 1.67 and cladding around the outside of index of refraction 1.45. Light is shown on the end of the fiber at an angle of 
relative to the fiber’s axis. What is the maximum angle with respect to the axis that light can be incident upon the fiber’s end and be fully transmitted along the fiber thanks to total internal reflection at the fiber/cladding interface?
A. 
B. 
C. 
D. 
E. 
F. 
Molecular Speeds: (a) At what Celsius temperature is the average kinetic energy of a helium gas atom equal to 6.21 × 10-21 J? The Boltzmann constant is 1.38 × 10-23 J/K .(b) What would be the temperature for radon gas?
Fill in the blank(s) with the appropriate word(s).
Consider wiggle formula 
for a transverse wave, where b and c are constants and ( ) is some arbitrary function. Is this a traveling wave model? If so, in what direction does it travel?
A. In the +x direction. B. In the ?x direction. C. The wave does not move. D. In the y or z direction because the wave is transverse.
The magnetic field at point P due to a 2.0-A current flowing in a long, straight, thin wire is 8.0 ?T. How far is point P from the wire? (?0 = 4? × 10-7 T ? m/
A) A) 2.0 cm B) 2.5 cm C) 4.0 cm D) 5.0 cm E) 10 cm