What might you find at the center of the Milky Way?
A. a region 10,000 light-years across containing no stars
B. a black hole with the mass of a few million Suns
C. the first stars that formed in the galaxy
D. a 10,000 solar mass star whose luminosity is 100 million solar luminosities
Answer: B
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The diagram above shows the life track of a 1 MSun protostar from the time it first begins to form until it reaches the main sequence, with four stages labeled. What is happening to the protostar's surface temperature and luminosity during Stage 3, when it is undergoing radiative contraction and its life track moves up and to the left?
A) Its surface temperature and luminosity increase. B) Its surface temperature remains the same and its luminosity decreases. C) Its surface temperature and luminosity decrease. D) Its surface temperature decreases and its luminosity increases. E) Its surface temperature and luminosity remain the same.
Two radio antennas are 120 m apart on a north-south line, and they radiate in phase at a frequency of 3.4 MHz. All radio measurements are made far from the antennas
If the east-west reference line passes midway between the two antennas, what is the smallest angle from the antennas, measured north of east, at which constructive interference of two radio waves occurs? (c = 3.00 × 108 m/s) A) 43° B) 22° C) 68° D) 47° E) 30°
The standard kilogram is a platinum-iridium cylinder 39 mm in height and 39 mm in diameter. What is the density of the material?
In an energy level transition from the n = 2 state to the n =1 state for a hydrogen atom a photon will be ___________
Fill in the blank(s) with correct word