Physics 308 Homework
RU Links
  Radford University
  Department of Physics
  RU Planetarium
  RUSMART pages (weather)

Spring 2014 Classes & Info
  PHYS 308
  PHYS 309
  PHYS 450
  My daily schedule
  My C.V.

Summer jobs/internships
  NSF REU Program (list of REU sites)

Other links
  The Nucleus (resources for
   physics/astronomy undergrads)
  Pre-Health information
   pics from the north pole trip
   the picture from the trip
  Simple 2-liter water rocket
  American Institute of Physics

Homework #7: Due Friday, March 20, by 5:15pm.

  1. What electric field is required to accelerate an electron from rest to 0.32c within a distance of 18cm? Assume the electric field is uniform. And recall from physics-2 that E=V/d for uniform E fields.
  2. An electron has been accelerated to a speed of 0.27c (27% the speed of light). The electron is traveling due north in a region where Earth's magnetic field has a strength of 52,000nT, and points at an angle of 55° below the horizontal. As in class, the horizontal component of the field points due north.
    (a) What potential (i.e., voltage) was required to accelerate the electron to this speed? Yes, this is physics-2 electric work-energy.
    (b) Find the final equation (numbers, units, unit vectors) for the force on the electron. You must use x for east, y for north and z for straight up from Earth's surface.
    (c) By how much does this electron deflect from due north after it has traveled a distance of 20cm northward?
  3. An electron has been ejected from a supernova explosion and has a kinetic energy of 25MeV. Find (a) the speed of this electron (in some convenient units), and (b) the potential difference that the supernova applied to the electron to get it to go this fast.
  4. A proton from out sun hits Jupiter's magnetic field (perpendicularly) with a speed of 1.00x106m/s; assume the average value of this field throughout this problem is 35nT. Find (a) the Larmor radius of this proton's orbit in this field, (b) the Larmor frequency fL with which this proton goes around that circle, and (c) the electromagnetic power that this proton radiates while in this orbit.
   That's all for homework #7.