A person with normal eyesight uses a converging lens of focal length 10 cm as a magnifying glass to finish an engraving job. To see detail, he holds the lens very close to his eyes. At what minimum distance from the job must he hold the lens?
A) 20 cm B) 30 cm C) 14 cm D) 9.4 cm E) 7.1 cm
E
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The totally eclipsed Moon glows coppery red because sunlight reaches the Moon's surface after passing through Earth's atmosphere
a. True b. False Indicate whether the statement is true or false
Uncertainty Principle Using Momentum and Position: Suppose that the speed of an electron traveling 2.0 km/s is known to an accuracy of 1 part in 105 (i.e., within 0.0010%). What is the least possible uncertainty within which we can determine the position of this electron? (melectron = 9.11 × 10-31 kg, h = 6.626 × 10-34 J ? s)
A. 2.0 mm B. 5.8 mm C. 14 mm D. 14 cm E. 8.5 nm
The temperature of the innermost part of the spinning gas near our galaxy's central black hole is:
A) 2.7 K. B) 300 K. C) 10,000 K. D) over 1,000,000 K. E) varying rapidly from 300 K to 1,000,000 K.
Three point charges are placed on the x-axis. A charge of +2.0 ?C is placed at the origin, -2.0 ?C to the right at x = 50 cm, and +4.0 ?C at the 100 cm mark
What are the magnitude and direction of the electrostatic force that acts on the charge at the origin? (k = 1/4??0 = 8.99 × 109 N ? m2/C2)