A velocity selector uses a fixed electric field of magnitude E and the magnetic field is varied to select particles of various energies. If a magnetic field of magnitude B is used to select a particle of a certain energy and mass, what magnitude of magnetic field is needed to select a particle of equal mass but twice the energy?
a. 0.50 B
b. 1.4 B
c. 2.0 B
d. 0.71 B
e. 1.7 B
D
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A ray of light traveling in water (n = 1.33 ) hits a glass surface (n = 1.50). At what angle, with the surface, must the incident ray be in order that the polarization of the reflected ray is the greatest?
A) 53.1° B) 33.7° C) 36.9° D) 41.6° E) 48.4°
The electron density in copper is 8.49 × 10^28 electrons/m3 . The electron charge is e = -1.60 × 10^-19 C. When a 1.00 A current is present in a copper wire with a 0.40 cm2 cross-section, the electron drift velocity, in m/s, with direction defined relative to the current density, is
a. -1.84 × 10^-6. b. +1.84 × 10^-6. c. -1.84. d. -5.43 × 10^5. e. +5.43 × 10^5.
A pair of parallel conducting plates have potentials of -17 V and 55 V, respectively. An electron is ejected from the plate at potential -17 V and travels to the plate at 55 V. What is the speed of the electron as it strikes the 55 V plate, assuming it left the -17 V plate from rest? The mass of the electron is 9.11 x 
kg.
a. 
b. 
c. 
d. 
Which of the following people did NOT accept a heliocentric model for the universe?
a. Kepler b. Copernicus c. Tycho d. Galileo e. Newton