Download PHYSICS 30 ELECTRIC FIELDS ASSIGNMENT 4 55 - ND

PHYSICS 30 ELECTRIC FIELDS ASSIGNMENT 4 55 MARKS
For each of the following questions complete communication must be shown. Communication consists of an introduction to
the physics of the situation, diagrams, word explanations and calculations in a well laid out formula, substitution, answer
format.
1. In a physics demonstration, a student inflates a balloon by blowing into it. The end of the balloon is then tied. The
balloon is rubbed with fur and develops an electrostatic charge. The balloon is placed against the ceiling and released. It
remains "stuck" to the ceiling. (10 marks)
The teacher then presents the following challenges to the students:
-explain how the balloon received the electrostatic charge
-explain why the balloon is attracted to the ceiling
-provide a procedure that would determine if the charge on the balloon is positive or negative. Include a list of any
additional equipment needed.
-provide a procedure that could be used to determine if there is a relationship between the amount of rubbing and the
amount of charge developed on an inflated balloon. Include a list of any additional equipment needed.
Provide a response to each of the teacher's challenges.
2. Two identically negatively charged graphite-coated polystyrene spheres each have a mass of 3.2 x 10 -3 kg. One
sphere is mounted on an insulating stand and the other is suspended by an insulating thread.(10.00 marks)
The sphere on the stand is placed on a table. The suspended sphere is arranged so that both spheres are the same
height above the table and their centers are 2.5 x 10-2 m apart. The thread makes an angle of 4.1° with the
vertical.
Determine the charge on the suspended sphere. In your response, sketch the free-body diagram of the forces acting
on the suspended sphere, sketch a vector addition diagram consistent with the vector analysis method you are
choosing, and state all necessary physics principles and formulas.
SMolesky@Notre Dame
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PHYSICS 30 ELECTRIC FIELDS ASSIGNMENT 4 55 MARKS
3. In a modified Millikan apparatus, a small, charged object that has a mass of 3.8 × 10 -15 kg is suspended by the
electric field that is between charged parallel plates. The table below shows how the balancing voltage depends on the
distance between the plates. (10 marks)
Provide a graph of the balancing voltage as a function of the plate separation, with the manipulated variable on the
horizontal axis.
• Calculate the slope of the graph, and describe the physical quantity or quantities that this slope represents.
• Using the slope, or another suitable averaging technique, determine the magnitude of the charge on the suspended
mass.
• Determine the balancing voltage required when the plates are separated by 50.0 mm.
Clearly communicate your understanding of the physics principles that you are using to solve this question. You may
communicate this understanding mathematically, graphically, and/or with written statements.
SMolesky@Notre Dame
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PHYSICS 30 ELECTRIC FIELDS ASSIGNMENT 4 55 MARKS
Choose the best response and place your answers, using HB pencil, on the Scantron sheet provided. Work must
be shown to receive credit for any answer.
1. Compared to the charge on a proton, the charge on an electron has the
a.
c.
opposite sign and a smaller magnitude
same sign and a smaller magnitude
b.
d.
opposite sign and the same magnitude
same sign and the same magnitude
2. While studying electrostatics, some students made these statements.
1.
2.
3.
4.
Like charges placed on plastic strips will repel each other.
Two glass rods that have been rubbed will tend to repel each other.
A body with a net negative charge repels any body that has a net negative charge.
An object with a net positive charge repels any object that has a net positive charge.
Which statements represent correct inferences?
a. 1 and 2 only
b. 3 and 4 only
c.
1, 3, and 4 only
d.
2, 3, and 4 only
3. When a charged rod is close to a neutral electroscope, the leaves of the electroscope are
observed to spread apart. While the charged rod is held close to, but not touching, the knob
of the electroscope, one can infer that:
a. only the leaves have a charge similar to that of the rod
b. only the leaves have a charge opposite to that of the rod
c. both the leaves and the knob have a charge similar to that of the rod
d. both the leaves and the knob have a charge opposite to that of the rod
4. In an electrostatic experiment, students want to place a negative charge on an electroscope by induction. Together
with the electroscope, what minimum equipment will be required by the students?
a.
c.
Hard rubber rod only
Two oppositely charged objects only
b.
d.
Negatively charged object only
Positively charged object and a ground only
5. Newton’s Law of Universal Gravitation has a mathematical relationship similar to the one developed by
a.
Coulomb
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b.
Einstein
c.
Lenz
d.
Ohm
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PHYSICS 30 ELECTRIC FIELDS ASSIGNMENT 4 55 MARKS
6.
Electrostatic Pendulum
A small balloon is suspended from a support by an insulated thread 10.0 cm long, as shown in the diagram. A
negatively charged ebonite rod is touched to the balloon and then returned to a position 2.00 cm from the
equilibrium position of the balloon, as shown in the diagram.
The charge product of the ebonite rod and the balloon, expressed in scientific notation, is _____ x 10-13 C2.
(Record all three digits of your answer on the answer sheet.)
a.
8.7 x 108 N
b.
9.5 x 109 N
c.
2.2 x 1010 N
d.
8.3 x 1013 N
e.
1.6 x 1019 N
Use the diagram to answer the next two question(s).
Shown is a small charged sphere (S1) suspended by an insulating thread and another small charged sphere (S 2) that
is unable to move.
7. In reference to the diagram, the charges on S 1 and S2 are each + 4.0 x 10-6 C and each has a mass of 3.0 x 10–4
kg. If S1 is brought to a distance of 2.0 x 10–2 m from S2, then what will be the acceleration of S1?
a.
– 1.2 x 10-6 m/s2
SMolesky@Notre Dame
b.
– 2.2 x 10-6 m/s2
c. – 3.2 x 10-6 m/s2
d. – 4.2 x 10-6 m/s2
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PHYSICS 30 ELECTRIC FIELDS ASSIGNMENT 4 55 MARKS
8.
In reference to the diagram, when S1 is brought to a distance of 2.00 x 10–2 m from S2, the acceleration of S1 is
3.00 x 1010 m/s2. If S1 is brought to a distance of 4.00 x 10–2 m from S2, then the magnitude of the acceleration of
S1 will be b x 10w m/s2.
The value of b is__________. m/s2
(Round and record your answer to three digits )
9. The units for electric field strength, in fundamental units, are:
a.
b.
c.
d.
10.
With reference to the directions above, given the number to match each of the descriptions below:
The values of a, b, c, and d, are _____, _____, _____, and _____.
(Record all four digits of your answer in the numerical-response section on the answer sheet.)
SMolesky@Notre Dame
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PHYSICS 30 ELECTRIC FIELDS ASSIGNMENT 4 55 MARKS
11. The electric field at point P in the diagram below is 8500 N/C directed to the right. What is the size and
polarity of charge q2? (1 C = 1.0 x 10-6 C)
POLARITY
a.
c.
+
+
SIZE
6.2 C
14 C
b.
d.
POLARITY
SIZE
–
–
6.2 C
14 C
12. Use the following information for the next question:
On a hot summer day, a mountain climber attempts to reach the summit of a local mountain. Halfway, the climber
stops on a ledge for a rest as large thunder clouds form overhead. Removing his backpack., he notices an strange
bluish glow, known as St. Elmo's Fire, surrounding the metal ice pick that is strapped onto the backpack. He
quickly seeks shelter until the thunder clouds move away.
The events that must occur in order for the phenomenon known as St. Elmo's Fire to appear are:
1) Air molecules nearest the ice pick separate into negative and positive ions.
2) Electrons in the metal ice pick concentrate near one end of the pick.
3. An electric field is created between the negative bottom of a cloud and the positive surface of Earth.
4) The negative and positive ions recombine, releasing energy as light.
Place the events in the correct sequence for the production of the eerie glow.
(Record your answer on the answer sheet
.)
13. A small charge of 6.00 nC is moved from a position with an electric potential of 350 V to a position with an
electric potential of 650 V.
The electric potential difference between the two positions is:
a.
300 V
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b.
650 V
c.
350 V
d.
950 V
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PHYSICS 30 ELECTRIC FIELDS ASSIGNMENT 4 55 MARKS
14. A 6.0 x 10-6 C charge is located 4.0 m from a -3.0 x 10-6 C charge. What is the electric potential at P, halfway
between the charges?
a.
-4.1 x 10-2 V
b.
6.8 x 103 V
c.
1.3 x 104 V
d.
5.0 x 104 V
15. Two long, parallel plates are separated by 0.028 m and have a potential difference between them of 80 V, as
shown below. Point P is located midway between the plates. What is the potential difference between point P and
one of the plates?
a.
0V
b.
40 V
c.
80 V
d.
160 V
16. Two Charges in the Electric Field of a Point Charge
In comparison, Charge A has:
a. more potential and more potential energy than Charge B
b. the same potential and less potential energy than Charge B
c. the same potential and more potential energy than Charge B
d. less potential and less potential energy than Charge B
17. The product of charge and potential difference equals:
a.
electric potential
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b.
electric field intensity
c.
capacitance
d.
energy
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PHYSICS 30 ELECTRIC FIELDS ASSIGNMENT 4 55 MARKS
18.
In a Geiger-Muller tube (a type of radiation detector) argon atoms are ionized by incoming radiation. The electrons
produced are accelerated from rest by a potential difference of 4.05 x 10 2 V. The speed of the electrons when they
strike the collecting anode is b x 107 m/s.
The value of b is ____________.
(Round and record your answer to three digits.)
19. The diagram shows a particle with a charge of 1.60 x 10 –8 C between two large, charged parallel plates that are
35.0 cm apart. The electric field intensity between the plates is 2.00 x 10 4 N/C.
If the particle moves under the influence of the electric field, what will be its kinetic energy just before hitting the
negative plate?
a.
1.12 x 10–4 J
b.
1.22 x 10–4 J
c.
1.32 x 10–4 J
d. 1.42 x 10–4 J
20. Which one of the following situations results in a conventional current that flows westward?
a. beam of protons moves eastward
b. an electric dipole moves westward
c. a beam of electrons moves westward
d. a beam of electrons moves eastward
e. a beam of neutral atoms moves westward.
21. The current through a light bulb is 2.0 A. How much electric charge passes through the light bulb in one
minute?
a.
60 C
SMolesky@Notre Dame
b.
2.0 C
c.
120 C
d.
240 C
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PHYSICS 30 ELECTRIC FIELDS ASSIGNMENT 4 55 MARKS
22. A beam of electrons is directed into the electric field between two oppositely charged parallel plates, as shown
in the diagram below.
The electrostatic force exerted on the electrons by the electric field is directed
a.
c.
into the page
toward the bottom of the page
b.
d.
out of the page
toward the top of the page
23. Two charged parallel plates are spaced 1 mm apart. A voltage difference of 9 V is placed across them. What is
the magnitude of the electric field between the plates?
a.
0.009 V/m
b.
0.09 V/m
c.
9.0 V/m
d.
90 V/m
e.
9000 V/m
24. A student performs Millikan's oil-drop experiment in which a latex sphere with a mass of 5.00 x 10 -16 kg is
suspended in an electric field between plates that are 9.00 x 10 -3 m apart. To keep the sphere suspended, the
potential difference between the plates cannot be greater than
a.
3.14 x 10-3 V
b.
3.07 x 104 V
c.
2.76 x 102 V
d.
1.80 x 1013 V
d.
-4.80 x 10-19 C
25. The net charge, in coulombs, on an oil droplet that has lost three electrons is:
a.
+5.33 x 10-20 C
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b.
+4.80 x 10-19 C
c.
-5.33 x 10-20 C
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