Problem 1.1 A 10cm sphere charged with a car battery (12V), picks up a positive charge of +100pC. How many excess or deficient electrons are on the sphere?
Select One of the Following:
(a) 3.2× 109 deficient electrons
(b) 1.1× 1014 excess electrons
(c) 6.7× 1011 deficient electrons
(d) 9.5× 105 excess electrons
(e) 6.3× 108 deficient electrons
Homework Problem 1.2 Your standard number 2 mechanical pencil has a graphite lead with mass 0.05g. How many protons are in this quantity of graphite? The atomic mass of carbon is 12g/mole and the atomic number is 6.
Select One of the Following:
(a) 3.1× 1010protons
(b) 1.5× 1022protons
(c) 5.1× 1024protons
(d) 2.3× 1021protons
(e) 6.5× 1023protons
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Homework Problem 1.3 An insulating cylinder has height 5cm and radius 10cm. If it carries a uniform surface charge density σ = −1µC/m2 including the ends, compute the total charge of the cylinder.
Select One of the Following:
(a) Q = −2× 10−2C
(b) Q = −3× 10−4C
(c) Q = −5× 10−6C
(d) Q = −9× 10−8C
Homework Problem 1.4 A problem you should have easily been able to do in Phys 111, but I get asked it all the time when I ask for a good question on electricity and magnetism the first day of class. Suppose a human can confortably live in a spaceship accelerating at 1g = 9.81m
s2 , ignoring relativistic effects, how long does it take
the spaceship to reach the speed of light? Report your answer in years. You may use the approximate conversion 1yr = π × 107s.
Select One of the Following:
(a) 15.7yr
(b) 0.19yr
(c) 0.97yr
(d) 15, 000yr
Homework Problem 1.5 How does the mass of the electron compare with the mass of the proton?
Select One of the Following:
(a) The two masses are equal.
(b) The electron is slightly more massive than the proton.
(c) The electron is slightly less massive than the proton.
(d) The electron is greatly more massive than the proton.
(e) The electron is greatly less massive than the proton.
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Homework Problem 1.6 In the nuclear process “beta decay”, a neutron is converted into some other charged particles, one of which is a proton. Some neutral particles are also emitted. What other charged particle must be emitted in beta decay?
Select One of the Following:
(a) an electron or something with the charge of an electron
(b) two electrons or particles with total charge equal to two electrons
(c) a proton or something with the charge of a proton
(d) an electron and a proton
(e) No other charged particles are required.
Multiple-Choice Questions
Homework Problem 1.7 A patch of positive charge is placed on a conducting sphere. Where will the positive charge be at a later time? Assume no charge is lost to the environment.
Select One of the Following:
(a) The charge will remain in the same place.
(b) The charge will stay bunched together but will move around the surface of the conductor.
(c) The charge will separate as much as possible spreading over the surface of the conductor.
(d) The charge will transform into neutral charge and disappear.
(e) The charge will spread apart, but will eventually come back together.
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Homework Problem 1.8 Which of the following describes an experiment that demonstrates that there are at least two different types of electric charge?
Select One of the Following:
(a) Rub one pair of rods made of the same material – for example, glass – with felt. Observe that the glass rods repel one another.
(b) Charge a pair each of glass and rubber rods by rubbing them with felt. Observe that that (1) the glass rods repel each other, (2) the glass rods attract the rubber rods, and (3) the rubber rods repel each other.
(c) Charge a pair each of glass and quartz rods by rubbing them with felt. Observe that that (1) the glass rods repel each other, (2) the quartz rods repel the glass rods, and (3) the quartz rods repel each other.
Homework Problem 1.9 Can a charged object exert a force on an uncharged insulator? If yes, why; if no, why not?
Select One of the Following:
(a) Yes, by inducing an electrical polarization in the insulator; the insulator is then attracted to the charged object.
(b) Yes, by inducing an electrical polarization in the insulator; the insulator is then repelled by the charged object.
(c) No, because uncharged objects do not feel electrical forces.
(d) No, because only conductors are attracted to or repelled by charged objects.
(e) No, because an insulator does not permit the motion of electric charge.
Homework Problem 1.10 It used to be that one could count on a water pipe as a good “ground”. A “ground” is a continuous conducting path to a long conductor buried in the Earth. Today, plumbing often involves plastic pipes and valves. Explain why this makes a water pipe something we now have to be careful of as a ground.
Select One of the Following:
(a) Plastic is only a conductor part of the time.
(b) The plastic is an insulator and may prevent there from being a continuous path to ground.
(c) Water pipes do not go into the ground anymore and thus won’t be grounded.
(d) The plastic will prevent the water from absorbing the charge.
(e) The plastic will divert any charge going to ground into the water which will shock anyone who uses the water.
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Homework Problem 1.11 Which of the following describes an experiment that demonstrates that there are at least two different types of electric charge?
Select One of the Following:
(a) Rub one pair of rods made of the same material – for example, glass – with felt. Observe that the glass rods repel one another.
(b) Charge a pair each of glass and rubber rods by rubbing them with felt. Observe that that (1) the glass rods repel each other, (2) the glass rods attract the rubber rods, and (3) the rubber rods repel each other.
(c) Charge a pair each of glass and quartz rods by rubbing them with felt. Observe that that (1) the glass rods repel each other, (2) the quartz rods repel the glass rods, and (3) the quartz rods repel each other.
Homework Problem 1.12 After sliding down a plastic slide at the park, your hair stands on end. It continues standing on end even after you get off the slide. What does this imply?
Select One of the Following:
(a) It implies that you have picked up a net charge from the slide.
(b) It implies that your hair has become polarized.
(c) It implies that your hair is covered in water and has become a better conductor.
(d) It implies that your hair has become conducting.
(e) It implies that your hair has become insulating.
Homework Problem 1.13 When an object is grounded, its net charge is reduced to approximately zero. Is this consistent with the Law of Conservation of Charge, if so how?
Select One of the Following:
(a) It is not consistent with conservation of charge; charge is actually destroyed when an object is grounded. Conservation of Charge only applies in some cases.
(b) It is consistent with Conservation of Charge; charge is actually destroyed on the object, but an equivalent charge will be created somewhere else in the universe.
(c) It is consistent with Conservation of Charge; charge is not destroyed but is transferred to another object.
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Homework Problem 1.14 A negatively charged golf tube (plastic rod) is brought near an uncharged conducting bucket. A positively charged pith ball is suspended within the bucket. Select the figure that accurately shows how the pith ball will react.
Select One of the Following:
(a) Figure (a) (b) Figure (b) (c) Figure (c)
GT
conductor
+
_ _
pith
Figure (a)
GT
conductor
+
_ _
pith
Figure (b)
GT
conductor
+
_ _
pith
Figure (c)
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Open Response Questions
All questions in this section must be worked. One of the questions will be graded.
Homework Problem 1.15 A hula-hoop (a circular hoop) has radius 0.6m and linear charge density around its edge of 0.3µC/m. What is the total charge of the hoop in Coulombs?
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Homework Problem 1.16 Since 1982, a penny has contained 2.5grams of copper. The atomic weight of copper is 63.546g/mole and the atomic number is 29. How many electrons are in a penny?
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Homework Problem 1.17 In the following, explain each step carefully and provide a drawing. A Coke can is brought into the electric field of a negatively charged golf tube.
(a)What is the direction of the force on the Coke can and why?
(b)The Coke can is then grounded in the presence of the golf tube. The golf tube had negative charge then what is the sign of the charge on the Coke can?
(c)What is the direction of the force on the Coke can after grounding and why?

What is the pressure due to the water in pounds per square inch (psi) at the bottom of the static column of water 300 feet deep? Recall that pressure is density times acceleration due to gravity times the height—and be careful about the units. Question 16 options: a) 14.7 psi
b) 1470 psi
c) 62.4 psi
d) 130 psi
Save Question 17 (1 point)
How much electric power could be obtained from a small hydroelectric station if the elevation change were 90 meters and if 12,000 kg of water passed through the turbines every second, with the overall efficiency being 80%? Question 17 options: a) 8.8 kW
b) 1.5 MW
c) 8.5 MW
d) 12.5 MW Save Question 18 (1 point)
The total mass energy of 200 grams of carbon is ________. Question 18 options:
a) 18 QWh
b) 18 QCal
c) 18 QBtu d) 18 QJ Save Question 19 (1 point)
What is the purpose of a breeder reactor? Question 19 options:
a) reduce the threat of nuclear weapons proliferation b) reduce the thermal polution c) to extend the useful lifetime of our uranium d) reduce the amount of plutonium produced Save Question 20 (1 point)
How much thermal energy in joules is made available by cooling 1 cubic meter of rock from 240 degrees C to 100 degrees C? The specific heat is 2.4 J per cubic centimeter per degree C. Question 20 options:
24.0 billion J
33.6 billion J
240 million J
336 million J Save Question 21 (1 point)
Which isotope of uranium is particularly good for fission with thermal neutrons? Question 21 options:
a) uranium-238
b) uranium-236
c) uranium-235
d) uranium-233 Save Question 22 (1 point)
If the wind blows at a steady 10 m/s, the electric power generated in a particular windmill system is 200 W/square meter. How much energy could we get in a year per square meter through the use of this windmill? Question 22 options: a) 60 kWh
b) 500 kWh
c) 1000 kWh
d) 1750 kWh Save Question 23 (1 point)
Ocean thermal gradient heat engines would have an ideal (Carnot) efficiency of about _______. Question 23 options:
a) 7%
b) 17%
c) 25%
d) 1% Save Question 24 (1 point)
Gasohol is a blend of corn-based ethanol plus gasoline. What is the typical ethanol content in the gasoline sold at service stations that do provide gasohol? Question 24 options: a) 1-6%
b) 6-12%
c) 12-15%
d) 15-18%
Save Question 25 (1 point)
Tidal basins fill and empty on a regular schedule owing the orbit of the
moon. About how many high tides are there each year? Question 25 options: a) 365 b) 700 c) 12 d) we can’t predict that number Save Question 26 (1 point)
Chemical energy available in such reactions as one would find in a hydrogen fuel cell is a few electron-volts. Nuclear fission reactions one would find in a nuclear power reactor release about how many times greater energy? Question 26 options:
a) 10 million
b) 100 million c) 1 billion
d) 100 billion Save Question 27 (1 point)
Carbon-14 has a half-life of 5730 years. And yet, the earth is about a million times older than this. How is it possible that we see any carbon-14 around? Question 27 options:
a) decay is strongly suppressed within the earth, so it lasts much longer
b) because it is formed continously by cosmic rays arrriving from outer space
c) it ends up produced copiously in the earth at the end of a long decay-chain of radioactive nuclei
d) The half-life is long enough where there sill should be an abundance left on earth from its beginning.
Save Question 28 (1 point)
In a typical fission of uranium, the number of neutrons emitted is about ________. Question 28 options: a) zero to
1 b) 2 to 3
c) 10 to 12 d) 235 Save Question 29 (1 point)
In a D-T fusion reaction, how many protons are involved? Question 29 options:
a) 4
b) 3
c) 2
d) 1 Save Question 30 (1 point)
The net result of nuclear fusion processes within our sun which generate life- giving energy is ________. Question 30 options: a) converting helium to either deuterium, tritium, or free protons and neutrons
b) taking four protons and converting 2 to neutrons in the process of fusing them into helium c) converting all heavy elements to protons, because there’s nothing more stable d) taking two protons and two neutrons and fusing to form 2 deuterium Save

Good photovoltaic cells have an efficiency of approximately ________ Question 1 options: a) 2-6%
b) 28-38%
c) 14-17%
d) 38-58% Save Question 2 (1 point)
Hydroelectric power in the U.S. currently represents about ______ % of the total U.S. electricity. Question 2 options:
a) less than 1 b) 40 c) 1 d) 7 Save Question 3 (1 point)
A windmill system which produces 9 kW of electrical power when the wind is blowing at 4 m/s, will produce ______ kilowatts when the wind is blowing 8 m/s? Question 3 options:
a) 72
b) 36
c) 24 d)
18 Save Question 4 (1 point)
Radioactivity refers to ________. Question 4 options: a) conversion of mass within the nucleus to energy b) decay of nuclei induced with neutrons
c) thespontanious decay of atomic nuclei into lighter, more stable nuclei d) decay of nuclei which must involve a neutrino or an antineutrino Save Question 5 (1 point)
The Solar Constant, 2 calories per square centimeter per minute, is _______. Question 5 options: a) the average solar intensity at ground level
b) the annual amount of solar energy available at the top of the earth’s atmophere c) the solar power density at 93 million miles from the sun d) extremely variable Save Question 6 (1 point)
In 2003 the wind energy generating capacity in the U.S. was about _______. Question 6 options:
a) 6.4 GW
b) 6.4 MW
c) 6.4 kW
d) 6.4 TW Save Question 7 (1 point)
The spectrum of solar radiation above the earth’s atmosphere has its maximum in intensity _______. Question 7 options:
a) at a wavelength higher than does the spectrum reaching the surface of the earth
b) at the same wavelength as does the spectrum reaching the surface of the earth
c) at a wavelength lower than does the spectrum reaching the surface of the earth
d) is not related to the maximum in the spectrum reaching the surface of the earth Save Question 8 (1 point)
Your cottage foundation is made up of 800 cubic feet of concrete while the floor is made up of 200 cubic feet of oak. About how many Btu are required to raise the temperature of the foundation and floor by 30 degrees F? Given: 22 Btu per cubic feet per degree F for concrete and 25 Btu per cubic feet per degree F for wood. Question 8 options: a) 678,000 b) 150,000 c) 528,000
d) 1,500,000 Save Question 9 (1 point)
What is a thermal neutron? Question 9 options: a) a neutron with kinetic energy about 1/40 of an eV. b) a neutron with a kinetic energy about 5 MeV
c) one of the neutrons which is produced in a typical nuclear fission reaction d) a neutron inside any large nucleus Save
Question 10 (1 point)
Suppose you have a typical flat-plate solar collector with area 64 square feet. What is a reasonable number for the Btu per day collected as heat energy? Assume an efficiency of 50%. Question 10 options:
a) 8,000
b) 64,000
c) 16,000
d) 32,000 Save Question 11 (1 point)
About _______ % of the total energy consumed in the U.S. each year is currently supplied by solar energy. Recall that we use about 98 QBtu per year. Question 11 options: a) 10 b) 6
c) 0.06 d) 1 Save Question 12 (1 point)
What is the base material and the doping material typically used in photovoltaic cells to convert solar radiation into electrical energy? Question 12 options: a) silicon doped with uranium
b) carbon doped with hydrogen c) silicon doped with arsenic
d) antimony doped with silicon
Save Question 13 (1 point)
What is the typical size and voltage output of an individual solar cell? Question 13 options:
a) 2 inches diameter and about 0.5 volt b) 6 inches diameter and about 1 volt
c) 0.5 inch diameter and about 9 volts
d) 1 inch diameter and about 0.1 volts Save Question 14 (1 point)
A parabolic reflector ________ Question 14 options: a) focuses only the direct component of sunlight b) focuses only the diffuse component of sunlight c) focuses both the direct and diffuse components of sunlight
d) can be used for solare collection systems only if the overall efficiency is less than 5 % Save Question 15 (1 point)
The temperature of the surface of the sun is about 5800 K. Using Stefan’s law, find the power per unit area emitted by the sun assuming that the surface emissivity is ideal, i.e. epsilon=1. Question 15 options:
a) 16 MW/square meter
b) 64 MW/square meter
c) 100 MW/square meter
d) 6.4 GW/square meter Save