An electron cannot decay into two neutrinos. Which of the following conservation laws would be violated if it did: (a) energy, (b) angular momentum, (c) charge, (d) lepton number, (e) linear momentum, (f) baryon number?

41. An electron cannot decay into two neutrinos. Which of the following conservation laws would be violated if it did: (a) energy, (b) angular momentum, (c) charge, (d) lepton number, (e) linear momentum, (f) baryon number? (Several choices may be correct.)_____
42. A proton cannot decay into a neutron and a neutrino. Which of the following conservation laws would be violated if it did: (a) energy (assume the proton is stationary), (b) angular momentum, (c) charge, (d) lepton number, (e) linear momentum, (f) baryon number? (Several choices may be correct.) _______
43. Which conservation laws are violated in the proposed decay? Assume that the initial particle is stationary and the decay products have zero orbital angular momentum.
44. In the laboratory, one of the lines of sodium is emitted at a wavelength of 590.0 nm. In light from a particular galaxy, however, this line is seen at a wavelength of 614.3 nm. Calculate the distance (in ly) to the galaxy, assuming that Hubble’s law holds and that the Doppler shift of Eq. 37-36 applies. (______units)
45. What is the observed wavelength of the 656.3 nm (first Balmer) line of hydrogen emitted by a galaxy at a distance of 1.94 x 108 ly? Assume that the Doppler shift of Eq. 37-36 and Hubble’s law apply. (______nm)
46. If Hubble’s law can be extrapolated to very large distances, at what distance would the apparent recessional speed become equal to the speed of light? (_____ly)
47. At what rate does a star emit photons? For simplicity, assume that the star’s entire emission at the rate of 4.9 x 1026 W is at the single wavelength of 550 nm. (______nm)
48. The meter was once defined as 1 650 763.73 wavelengths of the orange light emitted by a source containing krypton-86 atoms. What is the photon energy of that light? (______eV)
49. Light from a certain lamp is brightest at a wavelength of 603 nm. What is the photon energy (in eV) for light at that wavelength? (______units)
50. Light strikes a metal surface, causing photoelectric emission. The stopping potential for the ejected electrons is 6.3 V, and the work function of the metal is 2.5 eV. What is the wavelength of the incident light (in terms of nm)? (_______nm)