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
You might also like to view...
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.
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