Power: A 9.0-V battery costs $1.49 and will run a portable CD player for 6.0 hours before running down and needing to be replaced. If this battery supplies a current of 25 mA to the player, what is the cost of the energy provided by the battery in dollars per kWh?
A. $11/kWh
B. $110/kWh
C. $1100/kWh
D. $11,000/kWh
Answer: C
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Two identical objects A and B fall from rest from different heights to the ground and feel no appreciable air resistance. If object B takes TWICE as long as object A to reach the ground, what is the ratio of the heights from which A and B fell?
A) hA/hB = 1/ B) hA/hB = 1/2 C) hA/hB = 1/4 D) hA/hB = 1/8
Pat is viewing the moon with her new telescope. She is using a 10. mm eyepiece. Which of the following eyepieces will double the magnification?
A) 40. Diopter B) 8. mm C) 200. Diopter D) 12. mm E) 5. Diopter
The focal lengths of the objective and the eyepiece of a microscope are 0.50 cm and 2.0 cm, respectively, and their separation adjusted for minimum eyestrain (with the final image at the viewer's far point) is 6.0 cm
The near point of the person using the microscope is 25 cm and the far point is infinity. (a) If the microscope is focused on a small object, what is the distance between the object and the objective lens? (b) If the microscope is focused on a small object, what is its final magnification?
An electromagnetic wave with components Ey = Eo sin(kx - ?t) and Bz = Bo sin(kx - ?t) is a wave traveling with a speed of
A) ?. B) ?/k. C) k. D) k/?. E) ?/k2.