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Physics 2D Quiz 2

Version A Closed book. No work needs to be shown for multiple-choice questions. You may use a calculator. All values are in SI units unless explicitly stated otherwise.

1) A special tungsten filament at a temperature of 3700° K is 2 cm long and 1 mm in diameter. What is the total power output into EM radiation? (Assume that the filament has the shape of a round wire with the ends connected and that it radiates as a black body.)

a. 221 W

b. 668 W

c. 334 W

d. 75 W

e. none of the above

2) The photocurrent from a metal plate is cut off by a retarding potential of 1.6 V for radiation of wavelength 350 nm. Find the work function for the material.

a. 3.54 eV

b. 5.14 eV

c. 1.94 eV

d. 1.15 eV

e. none of the above

3) X-rays with an energy of 0.6 MeV undergo Compton scattering from a target. If the scattered rays are detected at 40 degrees relative to the incident rays, what is the wavelength of the scattered x-ray?

a. 2.07 X 10-9 m

b. 2.63 X 10-12 m

c. 2.07 X 10-12 m

d. 2.23 X 10-12 m

e. none of the above

4) Unpolarized light from the sun has an intensity of 900 Watts per square meter. This light is sent though a series of 4 polarizers. This first is along the x axis. The second, third, and fourth are at angles of 30 degrees, 60 degrees, and 90 degrees from the x axis. What is the intensity of light coming out of the polarizers?

a. 292 W m-2

b. 190 W m-2

c. 0 W m-2

d. 56 W m-2

e. none of the abovePhysics 2D Quiz 2

5) A beam of α particles with fixed kinetic energy is normally incident on a piece of gold foil. (a) If 1000 particles per minute are detected at a scattering angle of 10°, how many per minute will be counted at 120° if the kinetic energy of the incident α particles is reduced by a factor of 3?

a. 0.103

b. 0.0114

c. 0.114

d. 0.923

e. none of the above

6) A spectral line of sodium is observed using a diffraction grating with slit spacing of 3 microns. Aside from the very bright line at zero deflection angle, the lowest angle at which the spectral line is observed is 7.4 degrees. What is the wavelength of photons in that line?

a. 1.29 microns

b. 386 fm

c. 129 nm

d. 386 nm

e. none of the above

7) A Hydrogen atom makes a transition from the n=3 level to the n=2 level. What is the energy of the emitted photon?

a. 1.51 eV

b. 13.6 eV

c. 2.27 eV

d. 1.89 eV

e. none of the above

8) What is the de Broglie wavelength of an electron with a kinetic energy of 2 eV?

a. 0.867 nm

b. 620 nm

c. 312 nm

d. 12.2 nm

e. none of the above

9) If the size of a proton is of the order of 1 fm (10-15 m), what minimum kinetic energy must an electron beam have in order to “see” protons, inside a nucleus using electron scattering?

a. 10 MeV

b. 110 MeV

c. 1300 GeV

d. 1.2 GeV

e. none of the abovePhysics 2D Quiz 2