Suppose that an astronomer discovers an active galaxy, and that the intensity of the radiation from the galactic nucleus fluctuates in intervals of 8 minutes. Based on her observations, the astronomer should infer that the active nucleus of this galaxy is about ________ in diameter. (Hint: It takes light about 8 minutes to reach Earth from the Sun.)
A. 8 AU
B. 8 light-years
C. 1 AU
D. 1 Mpc
Answer: C
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Energy in Nuclear Reactions: An excited src="https://sciemce.com/media/4/ppg__cp1pbb0313192044__f440g1q10g6.jpg" style="vertical-align: -21.0px;" />Ba: 143.922845 u
U* nucleus undergoes fission into two fragments as follows:
U*? 
Ba + 
KrThe following atomic masses are known:
Kr: 91.926270 u
U*: 236.045563 uWhat is the reaction energy released during this fission reaction? (1 u = 931.5 MeV/c2)
A. 150 MeV
B. 160 MeV
C. 170 MeV
D. 180 MeV
E. 190 MeV
Most of the energy released during a supernova is emitted as neutrinos
Indicate whether the statement is true or false
In a region of space where the magnetic field of the Earth has a magnitude of 80 ?T and is directed 30° below the horizontal, a 50-cm length of wire oriented horizontally along an east-west direction is moved horizontally to the south with a speed of 20 m/s. What is the magnitude of the induced potential difference between the ends of this wire?
A. 0.45 mV B. 0.35 mV C. 0.30 mV D. 0.40 mV E. 0.69 mV
What statement below best describes the refraction of light?
a. The absorption of light as it travels though a dense, transparent material. b. The spreading out of white light according to wavelength. c. The change in direction of a light ray as it passes to a medium of different optical density. d. The change in direction of a ray of light as it reflects off a surface.