Briefly explain why radiation was trapped for 380,000 years during the era of nuclei, and why the cosmic background radiation was formed at the end of this era
What will be an ideal response?
During the era of nuclei, the universe consisted of a hot plasma of hydrogen nuclei, helium nuclei, and free electrons. Throughout this era, photons bounced rapidly from one electron to the next, just as they do deep inside the Sun today, never managing to travel far between collisions. If a nucleus managed to capture an electron to form a neutral atom, one of the photons quickly ionized it. This era came to an end when the expanding universe had cooled down to about 3,000 K. At this temperature, the hydrogen and helium nuclei were able to capture electrons and form stable, neutral atoms for the first time. With all electrons bound into atoms, the photons were, for the first time, able to stream freely across the universe. It is this radiation that forms the cosmic microwave background radiation.
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When water vapor changes phase to become water in a cloud, the surroundings become
A) cooler. B) warmer. C) both of these D) neither of these
Spectra for the Cygnus loop and the Orion nebula are shown above. Judging from their spectra, how would these two objects look to the naked eye (assuming they were bright enough for colors to be distinguished)?
A) The Cygnus loop would appear red, and the Orion nebula would appear blue. B) The Cygnus loop would appear red, and the Orion nebula would appear red. C) The Cygnus loop would appear blue, and the Orion nebula would appear blue. D) The Cygnus loop would appear blue, and the Orion nebula would appear red.
A(n) ______________ is any circle on the surface of a sphere whose center is at the center of the sphere
Fill in the blank(s) with correct word
Which change will not affect the kinetic energy of the most energetic electrons emitted in the photoelectric effect?
a. changing the frequency of the light b. changing the metal the light is hitting c. changing the brightness of the light d. All of the above will affect the electron's kinetic energy.