Download 1. An electron has a mass of 9.11 x 10 kg and its charge is

1. An electron has a mass of 9.11 x 10 -31 kg and its charge is -1.6 x 10-19 C. The electron is
released from rest in a vacuum between two flat, parallel metal plates that are 10 cm apart. The
potential difference across the plates is 750 volts. The electron is released near the negative
plate. What is its speed just before it strikes the positive plate?
2. A proton is traveling with velocity v, to the right, through a magnetic field pointing into the page
as indicated in the figure below.
(a) Indicate with an arrow the direction of the magnetic force on the proton.
(b) The mass of the proton is 1.67 x 10 -27 kg, its charge has a magnitude of 1.6 x 10 -19 C, its
speed is 1.55 x 105 m/s, and the magnetic field strength is 18.5 x 10 -3 T. Find the
magnitude of the magnetic force on the proton.
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3. A magnetic field is pointing out of the paper as indicated in the figure below. The coil contains
100 loops of wire. The loop diameter is 15 cm. The magnetic field is reduced from 1 T to zero
T in 16 seconds.
(a) While the magnetic field is changing, indicate the direction of the induced current,
drawing either a clockwise or counter clockwise arrow.
(b) What is the magnitude of the induced emf while the field is changing?
4. An arrow shaped object is placed 2 cm in front of a concave, spherical mirror whose radius of
curvature is 8 cm. The arrow is perpendicular to the principle axis, which passes through the
center of the mirror. Assume the arrow is much shorter than 8 cm.
(a) Locate the position of the image by constructing a ray diagram below.
(b) Is the image real or virtual?
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5. For the circuit shown below, calculate the voltage across, current through and power
requirements of the 8.0 ohm resistor when 15 volts are applied across the terminals.
R2=8.0 
R3=12.0 
R1=4.0 
R4=6.0 
R5=10.0 
6. A double slit diffraction experiment is set up with a slit separation of 2 x 10 -4 m, and screen
distance of 0.8 m. The distance from the central maximum to the second bright fringe from the
central maximum is 3.9 x 10-3 m. Approximately what is the wavelength of the light?
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7. What is the DeBroglie wavelength of a neutron whose kinetic energy is equal to the average
kinetic energy of an ideal gas of neutrons at 4 degrees K?
8. A five gram conducting sphere with a charge of 20 micro-coulombs hangs by an insulating
thread in an electric field produced by two plates separated by 8.0 cm. What potential across the
plates will cause the sphere to hang at 25 degrees to the vertical?
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9. A hollow tube of length L, open at both ends as shown above, is held in midair. A tuning fork
with a frequency fo vibrates at one end of the tube and causes the air in the tube to vibrate at its
fundamental frequency. Express your answers in terms of L and fo.
a. Determine the wavelength of the sound.
b. Determine the speed of the sound.
c. Determine the next higher frequency at which this air column would resonate.
The tube is submerged in a large graduated cylinder filled with water. The tube is slowly
raised out of the water and the same tuning fork, vibrating with a frequency fo, is held a fixed
distance from the top of the tube.
d. Determine the height h of the tube above the water when the air column resonates for the
first time. Express your answer in terms of L.
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10. Two radioactive isotopes are extracted from spent nuclear fuel and placed in a metal container,
which is then sealed and deposited in a nuclear waste disposal facility. The graph above shows
how many nuclei of isotopes 1 and 2 remain as a function of time.
a. From the graph, determine the half-life of isotope 1 and the half-life of isotope 2.
b. At time t = 10 years, which isotope is decaying at the greater rate? Explain your
reasoning.
c. What type of radiation (alpha, beta or gamma) would be most likely to escape through the
container walls?
d. What characteristics of the type of radiation named in part (c) distinguish it from the
other two?
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