The efficiency of classroom-demonstration lasers is typically
A) about one percent.
B) about ten percent.
C) about twenty percent.
D) more than twenty percent.
Answer: A
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Two equal point charges Q are separated by a distance d. One of the charges is released and moves away from the other due only to the electrical force between them
When the moving charge is a distance 3d from the other charge, what is its kinetic energy?
What is the giant impact hypothesis for the origin of the Moon?
A) The Moon originally was about the same size as Earth, but a giant impact blasted most of it away so that it ended up much smaller than Earth. B) The Moon formed just like Earth, from accretion in the solar nebula. C) The Moon formed from material blasted out of Earth's mantle and crust by the impact of a Mars-size object. D) The Moon formed when two gigantic asteroids collided with one another.
When a 12.0-V battery causes 2.00 ?C of charge to flow onto the plates of an air-filled capacitor, how much work did the battery do?
A) 24.0 ?J B) 12.0 ?J C) 144 ?J D) 576 J
All the following statements are true. Which of them are considered to be "exceptions" to the general trends described by the first three major features of the solar system?
A. Pluto is in the outer solar system but is ice-rich in composition. B. Jupiter's largest moon, Ganymede, is even larger than Earth's moon. C. Our Moon has a diameter more than 1/4 the diameter of Earth. D. Venus rotates in a direction opposite to the rotation of the other terrestrial planets. E. Uranus rotates with an axis tilt that lies nearly in the ecliptic plane.