{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

physics7C-Spring05-mt2-Battaglia-exam

physics7C-Spring05-mt2-Battaglia-exam - Physics 70 Section...

Info icon This preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
Image of page 1
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Physics 70 Section 2 Spring 2005 Midterm II, April 5, 2005 Prof. Marco Battaglia Choose four out of the five proposed problems. The test duration is 110 minutes. 1. The Fresnel equation gives the reflection coefficient R“ for waves parallel to the plane of incidence as R“ = :2: 31:43: , where the angles of incidence 91 and refraction 02 are defined by the Snell’s law. 1) Derive the analytic expression of the Brewster’s angle, at which the reflected light is fully polarised in the plane perpendicular to the plane of incidence. 2) Find the value of the Brewster’s angle for light reflected from a water surface. 2. A B particle, with mass=5.2 GeV/c2, is produced with a momentum p$=40 GeV / c. 1) Compute the value of 7 for the B particle. 2) The decay generates two identical pion particles, 7r, each with mass=0.14 GeV/c2, such that the momentum of one of the pions,‘ in the decaying B rest frame, projected along the line of flight of the B in the lab, is pay 122 GeV/c. Compute the angle between the two pions both in the B particle frame and in the laboratory frame. Do these angles depend on pm: 1 ? 3. A cosmic ray eihseriment is conducted using two detectors: the first is located at an altitude of 2000 m and the second at 500 m. The first detector counts 550 muons/hour and the second 400 muons / hour. The difference in counts is entirely due to the decay of muons according to the exponential law I (t) = I (0)?” T. The decay time T for muons has been measured to be 2.25 us, its mass is M# = 0.105 GeV/cz. 1) Determine the speed of the muons assuming Galilean relativity and comment whether the result is acceptable. _ 2) Determine the energy of the muons using the relativistic prescriptions. (Assume the mucus to travel along a" trajectory normal to the earth surface and, for point 2), approximate the muon velocity with c in computing the transit time). 4. The relation E = mc2 suggests that a photon 7 of sufficient energy E, = hl/ can generate an e‘e+ electron-positron pair. 1) Can the pair creation process occur in vacuum (justify the answer) ? 2) Which is the minimum E.) for it to occur with an electron e as spectator: we ——> e+e"e ? 3) Which is the minimum Ely for it to occur with a nucleus N as spectator: 7N —> e+e’N ? (Assume the spectator to be at rest in the laboratory). 5. The light emitted by the SSA12 galaxy is measured in a spectrometer at the Keck II telescope. The A=1216 Angstrom Ly-a H line is observed at a wavelength of 8185 Angstrom. 1) Determine the 2 value for the redshift of the galaxy and its recessional velocity in units of c. 2) Estimate the resolving distance for two stars in this Galaxy emitting light at A=1216 Angstrom, knowing that the diameter of the telescope mirror is 10 m. (1 Angstrom = 10‘10 m, 1 ly = distance covered by light in one year. Take H0 2 20 km s'1 Mly"1 for the Hubble constant which relates the distance to the recessional velocity) ...
View Full Document

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern