Which types of galaxies have a halo component?
A) spirals only
B) ellipticals only
C) irregulars only
D) both spirals and ellipticals
D) both spirals and ellipticals
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A refracting astronomical telescope has objective and eyepiece lenses of focal lengths 38 cm and 0.40 cm, respectively. What is the angular magnification of this instrument?
a. 95 c. 27 b. 50 d. 19.6
In an isolated system of two bodies that exert gravitational forces on one another, the quantity (quantities) that remain(s) constant is(are)
a. the total energy of the system. b. the total angular momentum of the system. c. the angular positions of the two bodies. d. all of the above. e. only (a) and (b) above.
Absolute visual magnitude is the:
A) apparent magnitude of a star observed from Earth. B) luminosity of a star observed from a distance of 1000 pc. C) apparent magnitude of a star observed from a distance of 10 pc. D) luminosity of a star observed from Earth.
Motional Emf: It is known that birds can detect the earth's magnetic field, but the mechanism of how they do this is not known. It has been suggested that perhaps they detect a motional emf as they fly north to south, but it turns out that the induced voltages are small compared to the voltages normally encountered in cells, so this is probably not the mechanism involved. To check this out, calculate the induced voltage across the wingtips of a wild goose with a wingspan of 1.2 m if it is flying directly south at 13 m/s at a point where the earth's magnetic field is 5.0 ×10-5 T directed downward from the horizontal by 40?.
A. 0.50 mV B. 0.60 mV C. 0.78 mV D. 0.060 mV E. 0.25 mV