What is the best evidence for an extremely massive black hole in the center of the Milky Way?
A) The center of our galaxy hosts a pulsar that is spinning so fast that it could only be a black hole.
B) We observe stars vanishing in the center of the Galaxy as they are sucked into the black hole.
C) Huge amounts of X-rays are pouring out of the center of the galaxy.
D) The orbits of stars in the center of the galaxy indicate that the presence of 3 to 4 million solar mass object in a region no larger than our Solar System.
D
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Blue stars are hotter than red stars
a. True b. False Indicate whether the statement is true or false
What is the potential difference between the ends of bulb A?
A. 1.5 V
B. 1.2 V
C. 0.5 V
D. 0.3 V
E. 0.15 V
F. Some other value (specify)
Which one of the following statements concerning emf is true?
a) Emf is the work done in moving the current from one terminal to the other of an emf device. b) Emf is the work done in moving a single charge from one terminal to the other of an emf device. c) Emf is the force exerted on a single charge to move it from one terminal to the other of an emf device. d) Emf is the total charge moving from one terminal to the other of an emf device. e) Emf is the electromagnetic force that is exerted between the terminals of an emf device.
A ray of light strikes a thick sheet of glass (n = 1.5) at an angle of 22° with the normal. Find the angle of the ray reflected off the glass surface with respect to the normal
a. 33° b. 50° c. 14° d. 22° e. 15°