A permanent magnet is produced when
A. electrical fields exchange electrons with the magnetic fields.
B. electrons become stuck and cease to move.
C. current is made to circulate in a clockwise direction in a loop of wire.
D. magnetic fields of large groups of individual atoms are permanently aligned.
Answer: D
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If the acceleration vector of an object is directed anti-parallel to the velocity vector, then
A) the object is speeding up. B) the object is slowing down. C) the object is turning. D) the object is at rest. E) this situation would not be physically possible.
Which of the following describes what will happen to a light ray incident on a glass-to-air boundary at greater than the critical angle?
a. partial reflection, total transmission b. total transmission c. total reflection d. partial reflection, partial transmission
A small bulb is rated at 7.50 W when operated at 125 V. The tungsten filament has a temperature coefficient of resistivity a = 4.50 × 10^-3 / °C. When the filament is hot and glowing, its temperature is seven times room temperature (20 °C). What is the resistance of the filament (in ohms) at room temperature?
a. 234 b. 1 350 c. 2 080 d. 4 530 e. 5 630
General Questions: A fireman is sliding down a fire pole. As he speeds up, he tightens his grip on the pole, thus increasing the vertical frictional force that the pole exerts on the fireman. When the force on his hands equals his weight, what happens to the fireman?
A. The fireman comes to a stop. B. The fireman descends with slower and slower speed. C. The fireman descends with a smaller but non-zero acceleration. D. The fireman continues to descend, but with constant speed. E. The acceleration of the fireman is now upward.