1. What is wave-particle duality? How does it apply to photons and electrons? Why do we not generally observe this in everyday life? 2. What is the Hubble Law? What does it say about the evolution of the universe? What does it have to do with redshift?

1. What is wave-particle duality? How does it apply to photons and electrons? Why do we not generally observe this in everyday life? 2. What is the Hubble Law? What does it say about the evolution of the universe? What does it have to do with redshift?

College Physics

1st Edition

ISBN:9781938168000

Author:Paul Peter Urone, Roger Hinrichs

Publisher:Paul Peter Urone, Roger Hinrichs

Chapter34: Frontiers Of Physics

Section: Chapter Questions

Problem 8PE: (a) Calculate The approximate age of the universe from the average value of the Hubble constant, To...

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3. Consider the following two universes: Universe I: flat, matter-dominated with no cosmological constant or radiation, in which a(t) = (t/to)2/3. Universe II: flat, radiation-dominated with no cosmological constant or matter, in which a(t) = (t/to) ¹/². a. Which universe is expanding the fastest? b. For each case, use the Hubble law to show that to = 3/(2H₁) and to = 1/(2H₁) for universes I and II respectively. c. Based on the previous question, which universe would be the youngest assuming a given Ho value?
1. What is escape velocity? 2. What does it mean to have a binding energy? 3. Under what conditions would you have to achieve in order for a satellite to escape the gravitational field of another body? 4. Why don't astronauts feel the effects of gravity while in orbit around Earth? 5. Why don't we feel the physical attraction from people around us, if there is a force of gravity between every obiect containing mass?
1. What is meant by a 'black' body ? How can we make an almost ideal blackbody in the lab ? 2. What is the UV catastrophe ? How it was solved ?
The mass density of our universe is measured to be about 10-29 kg/m3. If an arbitrary point is chosen as the center, how large is the radius of a spherical surface centered at the point so that the mass enclosed in the surface will become a blackhole observed by someone outside the surface? A. 4.2 trillion light years B. 420 billion light years C. 42 billion light years D. 4.2 billion light years Is the answer D? Thanks!
1. The current (critical) density of our universe is pe = 10-26kg/m³. Assume the universe is filled with cubes with equal size that each contain one person of m = 100kg. What would the length of the side of such a cube have to be in order to give the correct critical density? How many hydrogen atoms would you need in a box of 1 m³ to reach the critical density? The matter we know, which consists mostly of hydrogen, constitutes only 4.8% of the current critical energy density of our universe. So how many hydrogen atoms are actually in a box of 1 m3 in our universe? Deep space is very empty and a much better vacuum than we can obtain on earth in a laboratory.
1. What is Olber’s paradox? What are the underlying assumptions behind Olber’s paradox? How can this paradox be resolved? 2. Describe three pieces of evidence for wave-particle duality.
4. State the mathematical description for Wien displacement law, how this is tested in the lab ? 5. Starting from the Plank distribution, 2he Ba(A, T) = A5 1 - 1 Derive Wien displacement law by maximizing the distribution. 6. Use the Plank distribution to derive the Stefan-Boltzman Law.
Why does primordial nuclesythesis end about 3 minutes after the Big Bang ? select one : a. The number densities of photons is too large at this time and the photons induce fission , stopping nuclei formation b. The universe is tooo hot at t=3 minutes c. The number densities of neutrons and protons and other nuclei are too small at this time and fusion fades out . d. Deuterium has a lifetime of 3 minutes , so after this time no more deuterium survives as it decays away ?
Problem 2. The redshift is defined to be the quantity Job – Xem Xem where Aob and Aem are respectively the wavelengths at which radiation is observed and emitted. 1. Find the corresponding definition in terms of observed and emitted frequencies fob and fem. 2. The observed frequency of radio waves from a distant galaxy is 5 GHz. At the location of galaxy, the frequency is 6 GHz. Calculate the redshift of the galaxy. 3. If the galaxy was 500 Mpc away from the Milky way when the radio waves were emitted. How far away is this galaxy today?
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