What do we mean when we say the universe becomes transparent at 300,000 years after the Big Bang?
A: we can only see from one end of the universe to another if we existed before that time
B: electromagnetic radiation (light) can travel freely through the universe so we can see to large distances
C: Helium nuclei formed then and since they are transparent it was possible to see to larger distances
D: protons and neutrons formed then and since they are transparent it was possible to see to larger distances
E: the universe ends at that time
Ans: B: electromagnetic radiation (light) can travel freely through the universe so we can see to large distances
You might also like to view...
A loop of radius r = 3.0 cm is placed parallel to the xy-plane in a uniform magnetic field = 0.75 T
The resistance of the loop is 18 ?. Starting at t = 0, the magnitude of the field decreases uniformly to zero in 0.15 seconds. What is the magnitude of the electric current produced in the loop during that time? A) 0.79 mA B) 3.9 mA C) 1.7 mA D) 2.1 mA E) 0.20 mA
Emission nebulae are also called ________ because they are composed of ionized hydrogen
a. HI regions b. HII regions c. Bok globules d. HeI regions e. reflection nebulae
At the lower left of the Hertzprung—Russell diagram we find
A) supergiant stars B) red giant stars C) white dwarfs D) main sequence stars
Earth displays slower erosion than any other Terrestrial planet
a. True b. False Indicate whether the statement is true or false