A photocathode that has a work function of 2.4 eV is illuminated with monochromatic light having photon energy 3.5 eV. What is the wavelength of this light?
(c = 3.00 × 108 m/s, h = 6.626 × 10-34 J ? s, 1 eV = 1.60 × 10-19 J)
A) 350 nm
B) 330 nm
C) 300 nm
D) 380 nm
E) 410 nm
A
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A rod, with sides insulated to prevent heat loss, has one end immersed in boiling water 100°C and the other end in a water-ice mixture at 0.00°C
The rod has uniform cross-sectional area of and length of Under steady state conditions, the heat conducted by the rod melts the ice at a rate of every 34 seconds. What is the thermal conductivity of the rod? (The heat of fusion of water is What will be an ideal response?
According to author Norman Mailer from his book Of a Fire on the Moon, quoted in the opening section,
A) powerful new science-based technologies are bringing about a better life on this planet. B) the creation of Earth was a beautiful and spiritually significant event for the human race. C) intelligent extraterrestrial life forms probably exist in many places, and may visit Earth in the near future. D) the establishment of a technology base on the moon is a crucial step in the exploration of the solar system. E) science is moving us rapidly along new paths, but we haven't stopped to consider where those paths might lead.
One way to describe the "allowed" matter fields for an isolated hydrogen atom is that they are
A) the electromagnetic fields that can be produced by the orbiting electron. B) the various possible elliptical shapes for the orbit of the electron. C) the possible shapes of the electron's charge that will just "fit" around the nucleus. D) the possible standing waves that will just "fit" around the nucleus. E) the patterns that are spherically symmetric relative to the nucleus.
The observed evidence we have for black holes includes
A) X-rays that are thought to come from the center of a black hole. B) visible light that is thought to come from the center of a black hole. C) temperature measurement of certain extremely cold stars that are thought to be black holes. D) X-rays that are thought to come from gases that are outside of a black hole. E) observations of certain regions of space, larger than the largest known stars, that emit no light.