Back(II) Suppose that three main-sequence stars could undergo the three changes represented by the three arrows, A, B, and C, in the H–R diagram of Fig. 44–35. For each case, describe the changes in temperature, intrinsic luminosity, and size.
Why is it important to specify a reference frame when describing the motion of an object?
Why is it important to know if your reference point is moving when analyzing the motion of an object in physics?
Heavy nuclei often undergo alpha decay in which they emit an alpha particle (i.e., a helium nucleus). Alpha particles are so tightly bound together that it’s reasonable to think of an alpha particle as a single unit within the nucleus from which it is emitted. A 238U nucleus, which decays by alpha emission, is 15 fm in diameter. Model an alpha particle within a 238U nucleus as being in a one-dimensional box. What is the maximum speed an alpha particle is likely to have?
How many photons per second are emitted by a -mW CO2 laser that has a wavelength of mm?
Two stars, both of which behave like ideal blackbodies, radiate the same total energy per second. The cooler one has a surface temperature and a diameter times that of the hotter star.
(a) What is the temperature of the hotter star in terms of ?
(b) What is the ratio of the peak-intensity wavelength of the hot star to the peak-intensity wavelength of the cool star?
Draw an energy-level diagram, similar to Figure 38.21, for the He+ ion. On your diagram: Show the ionization limit.
What is the wavelength, in nm, of a photon with energy (a) 0.30 eV, (b) 3.0 eV, and (c) 30 eV? For each, is this wavelength visible, ultraviolet, or infrared light?
It might seem strange that in beta decay the positive proton, which is repelled by the positive nucleus, remains in the nucleus while the negative electron, which is attracted to the nucleus, is ejected. To understand beta decay, let's analyze the decay of a free neutron that is at rest in the laboratory. We'll ignore the antineutrino and consider the decay n → p⁺ + e⁻. The analysis requires the use of relativistic energy and momentum, from Chapter 36. What is the total kinetic energy, in MeV, of the proton and electron?
Identify the element for each of these electron configurations. Then determine whether this configuration is the ground state or an excited state. 1s2 2s2 2p6 3s2 3p6 4s2 3d2
A particle is described by the wave function mm where L = 2.0 mm. Determine the normalization constant c.
An electron is moving as a free particle in the -direction with momentum that has magnitude kg-m/s. What is the one-dimensional time-dependent wave function of the electron?
Which of the following is an inertial reference frame?
What is the angular momentum of a hydrogen atom in (a) a 6s state and (b) a 4f state? Give your answers as a multiple of ℏ .
A typical electron in a piece of metallic sodium has energy −E₀ compared to a free electron, where E₀ is the 2.36 eV work function of sodium. At what distance beyond the surface of the metal is the electron’s probability density 10% of its value at the surface?