A series LR circuit dissipates 60 W. The circuit is powered by a 120 V rms 60 Hz supply. If the current is 2.0 A rms, what is the power factor?
A. 0
B. 0.25
C. 0.50
D. 0.75
E. 1.0
B. 0.25
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A solar or lunar eclipse will occur
a. when the Sun is near the line of nodes of the Moon, and the Moon is new or full. b. any time the Moon is new or full. c. when the Sun is near the solstice, and the Moon is new or full. d. half-way through an eclipse year. e. when the Sun is near the equinox, and the Moon is new or full.
It is possible for a medium-mass star to collapse and form a white dwarf, but no planetary nebula
a. True b. False Indicate whether the statement is true or false
The 1920s represents the dawn of commercial radio. How would those investors interested in the new technology decided what growth possibilities there were? Would knowledgeable investors have drawn straight lines on regular or on semilogarithmic
graph paper? Why?
Starting from rest, a car accelerates down a straight road with constant acceleration a1 for a time t1, then the acceleration is changed to a different constant value a2 for an additional time t2 . The total elapsed time is t1 + t2 . Can the equations for motion with constant acceleration be used to find the total distance traveled?
a. No, because this is not a case of constant acceleration. b. Yes, use (a1 + a2)/2 as the average acceleration and the total time in the calculation. c. Yes, use a1 + a2 as the acceleration and the average time (t1 + t2)/2 in the calculation. d. Yes, break the problem up into 2 problems, one with the conditions for the first time interval and the other with the conditions for the second time interval, noting that for the second time interval the initial velocity is that from the end of the first time interval. When done, add the distances from each of the time intervals.