Why do some quasars have redshifts greater than 1?
A) They are made of different elements than any other objects in the universe.
B) They are very distant, with relativistic redshifts that take into account dilation of space-time, as Einstein predicted.
C) They are made of tachyons and thus are able to move away from us faster than the speed of light.
D) Einstein proved it is impossible to have a redshift greater than 1; these are all due to gravitational lensing tricking us.
E) They are moving towards us, which throws off our spectrometers.
B
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A metal has a Fermi level of 5.50 eV. At 1200 K, what energy will have a 90% occupancy probability?
A) 5.79 eV B) 5.73 eV C) 5.56 eV D) 5.44 eV E) 5.27 eV
An aquarium contains a 5-cm layer of water (n = 1.33) floating on top of carbon tetrachloride (n = 1.461). If the angle of incidence into the water from the air is 30°, what is the angle of refraction into the carbon tetrachloride?
a. 58° b. 69° c. 37° d. 20° e. 75°
The experimental observation(s) below that require(s) a quantum explanation for the photoelectric effect
a. is that more photoelectrons are emitted when the light frequency increases. b. is that the maximum kinetic energy of the photoelectrons is related linearly to the frequency of the light. c. is that every metal surface has a work function, a minimum amount of energy needed to free electrons. d. is that the stopping potential measures the kinetic energy of the photoelectrons. e. are all of the above.
A hypothesis that is scientific must have a test for proving it
A) right. B) wrong. C) either.