Concept explainers
Due to the presence everywhere of the cosmic background
Want to see the full answer?
Check out a sample textbook solutionChapter 44 Solutions
Fundamentals of Physics, Volume 1, Chapter 1-20
Additional Science Textbook Solutions
Physics for Scientists and Engineers: A Strategic Approach with Modern Physics (4th Edition)
Conceptual Physical Science (6th Edition)
Essential University Physics (3rd Edition)
Applied Physics (11th Edition)
- If the electrons gain this energy by collision between hydrogen atoms in a high temperature gas, find the minimum temperature of the heated hydrogen gas. The thermal energy of the heated atoms is given by 3 kB T 2, where the Boltzmann constant is 1.38 × 10-23 J/K. Answer in units of K.arrow_forward1.You are on an interstellar mission from the Earth to the 8.7 light-years distant star Sirius. Yourspaceship can travel with 70% the speed of light and has a cylindrical shape with a diameter of6 m at the front surface and a length of 25 m. You have to cross the interstellar medium with anapproximated density of 1 hydrogen atom/m3.(a) Calculate the time it takes your spaceship to reach Sirius.(b) Determine the mass of interstellar gas that collides with your spaceship during the mission.Note: Use 1.673 × 10−27 kg as proton mass.arrow_forwardSuppose your professor discovers dark matter, and it turns out to be a new type of subatomic particle which can share a state with one other particle – but no more – of the same type. In other words, the number of these (indistinguishable) particles in any given state can be 0, 1, or 2. (a) Derive the distribution function (analogous to the Bose-Einstein or Fermi-Dirac distribution) for the average occupancy of a state for particles of this type. It should be a function of e, µ, and kT. (b) What is the value of this distribution function at e = u? What value does the function approach for very large e? For very small e, under the assumption that u >> kT? (c) Suppose the "state" of the particle is defined only by its energy (do not consider spin, charge, etc.) Furthermore, suppose these particles are found in a system where the quantized energy levels are evenly spaced1 eV apart, and the lowest level has energy 0. What is the lowest possible energy of the system, if there are 10 of…arrow_forward
- Prove that the thermal conductivity could also be written as: neKB 3KBT m Where KB denotes the Boltzmann constant and m denotes the electron ng the expression of the electric conductivity o previously established he problem, prove that the Lorentz number is given by: 2 Steam Heat flow T- OT 2 E+ OT dx A dE dx 3 (KBY == { B E Figure 2 T-(17) E C E- 1 dE dx Candarrow_forwardIn discussing molecular rotation, the quantum num- ber J is used rather than 7. Using the Boltzmann distribution, calculate nj/no for ¹H³5Cl for J = 0, 5, 10, and 20 at T = 1025 K. Does ny/no go through a maximum as J increases? If so, what can you say about the value of J corre- sponding to the maximum?arrow_forwardDetermine lm , the wavelength at the peak of the Planck distribution, and the corresponding frequency ƒ, at these temperatures: (a) 3.00 K; (b) 300 K; (c) 3000 K.arrow_forward
- In the Debye model: (a) Starting from the general form of the density of states g(k)dk Debye frequency in terms of the speed of sound v and density N/ = (b) Show that the heat capacity at low temperatures is C = Nk (c) What is the heat capacity at high termperatures? Vk?dk 2π² (125+ (7) ³. find thearrow_forwardUse Boltzmann distribution to solve this problem.A system consists of 3, 000 particles that can only occupy two energy levels: a nondegen-erate ground state of 0.052 eV and a threefold degenerate excited state at 0.156 eV. IfT = 900 K,(a) find the number of particles at each energy level.(b) what is the total energy of the system?arrow_forwardYou are on an interstellar mission from the E arth to the 8.7 light-years distant star Sirius. Your spaceship can travel with 70% the spee d of light and has a cylindrical shape with a diameter of 6 m at the front surface and a le ngth of 25 m. You have to cross the interstel lar medium with an approximated density of 1 hydrogen atom/m3. (a) Calculate the time it takes your spaceshi p to reach Sirius. (b) Determine the mass of interstellar gas th at collides with your spaceship during the mi ssion.arrow_forward
- The Sun radiates almost like a perfect blackbody at a temperature of T= 5800 K. a) Show, using the Stefan-Boltzmann law, that the rate at which it radiates energy is - 4x1026 W. b) If you were at Earth's orbit, in space, how many Sun photons would reach you per second? Assume you have a mass of 70 kg, are spherical and full of water. You may need to find your cross sectional area and assume all Sun photons move in the same direction.arrow_forwardThe degeneracy pressure of the electrons can stabilize the collapse of a star due to gravity by equating the gravitational inward pressure with the outward electron gas degeneracy pressure. These cold stars called white dwarfs have small radii compared to their original size and this radius decreases as the original mass of the star increases. As the mass of a star increases, the electron energy increases to a point in which their energy has to be treated relativistically. (a) Evaluate the degeneracy pressure for ultra-relativistic electrons (problem 2, above). (b) As the pressure increases, the reaction e − + p → n + ν takes place. The neutrinos (ν) escape as matter is transparent to them, electrons and protons convert to neutrons until we are left with a neutron star. Using your expression for the degeneracy pressure obtained in (a) above, equate the gravitational pressureto the neutron degeneracy pressure (replace the electron’s mass in your degeneracy pressure expression from (a)…arrow_forwardSuppose a nanostructure is modeled by an electron confined to a three-dimensional region with sides of lengths L1 = 1.0 nm, L2 = 2.0 nm, and L3 = 1.5 nm and is subjected to thermal motion with a typical energy equal to 32kT, where k is Boltzmann’s constant. How low should the temperature be for the thermal energy to be comparable to (a) the zero-point energy, (b) the first excitation energy of the electron?arrow_forward
- Modern PhysicsPhysicsISBN:9781111794378Author:Raymond A. Serway, Clement J. Moses, Curt A. MoyerPublisher:Cengage Learning