Download Sample exam 2

Physics 203
Exam 2
A star is 12 light years from earth. If a spaceship travels at 0.98c,
a) how long does it take for a round trip from the mission controller’s point of view (the guy
who stays at home)
b) how much older is the pilot when he returns?
c) what does the space ship odometer read when it returns?
2. An electron with 50 MEV kinetic energy travels down a 3.2 km accelerator tube,
a) what is its speed?
b) how long does it take in the lab frame?
c) how long in the “electron’s frame”
3. When a metal is illuminated with light of frequency “f” the max kinetic energy of ejected
electrons is 1.3 ev. When this frequency is increased by 50% the ejected electron have up to
3.6 ev. What is the work function of the material?
4. Draw the energy level diagram for the first four levels of triply ionized Beryllium and find the
longest wavelength for any of the find the longest wavelength for any of the transitions within
this set.
5. In the ground state for a particle in an infinite potential well that extends from x=0 to x=L,
find the probability of locating the particle between x=L/4 and x= 3/4L.
6. What is the deBroglie wavelength for an electron which has been accelerated through 400,000
volts.