Who first attempted to find our position in the Galaxy, how did he do this, and why was his model flawed?
What will be an ideal response?
William Herschel relied on star counts, and found most stars lie near the plane of the Milky Way, and in about equal numbers in all directions within this plane. He naturally took this to mean we lay near the center of a thin disk about 10,000 light years across. But dust near us blocks the vast majority of the Galaxy in visible wavelengths, so Herschel's survey included less than 10% of the whole Galaxy.
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Which of the following statements best describes the difference between a refracting telescope and a reflecting telescope?
A) A refracting telescope uses a transparent glass lens to focus light, whereas a reflecting telescope uses a mirror to focus light. B) A refracting telescope produces refracted images, whereas a reflecting telescope produces reflected images. C) Reflecting telescopes make much clearer images than refracting telescopes of the same size. D) It is much easier to make a large refracting telescope than a large reflecting telescope.
The type of radio galaxy that reveals its motion through the intergalactic medium is called a:
A) quasar. B) dual lobe. C) bi-polar jet. D) head-tail. E) Seyfert.
A 50-cm wire placed in an east-west direction is moved horizontally to the north with a speed of 2.0 m/s
The horizontal component of the earth's magnetic field at that location is 25 ?T toward the north and the vertical component is 50?T downward. What is the emf induced between the ends of the wire? A) 10 µV B) 20 µV C) 30 µV D) 40 µV E) 50 µV
The speed of FM waves will be observed to be c = 2.9979 × 10^8 m/s when the antenna emitting the waves is
a. at rest relative to the receiving antenna. b. moving to the right of the detecting antenna at 0.5 c. c. moving to the left of the detecting antenna at 0.5 c. d. moving as described in (a), (b) or (c) above. e. moving at 2.9979 × 10^8 m/s.