Download Unit 3 Electricity and Magnetism Summative

Unit 3 Electricity and Magnetism Summative
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Name:___________
Modified True/False
/11
Indicate whether the sentence or statement is true or false. If false, change the identified word or phrase to make the
sentence or statement true.
____
1. Coulomb’s law is extremely accurate under the conditions that the spheres are small and that the spheres are
also small compared to the distance between them. ______________________________
____
2. One of the ways in which Newton’s law of universal gravitation differs from Coulomb’s law is that
gravitational force can only attract, whereas the electric force can only repel.
________________________________________
____
3. By convention, in electrostatic representations, electric fields start on negative charges and end on positive
charges. _____________________________________________
____
4. In two-dimensional diagrams of magnetic fields Xs are drawn to represent field lines pointing out of and
perpendicular to the page. _________________________
____
5. When a conductor is placed in a magnetic field, the force on the conductor is directly proportional to the
magnitude of the magnetic field. _________________________
____
6. Measurements of the magnetic field strength show that
____
7. A larger current is produced when a magnet is plunged into a solenoid by using a stronger magnet.
_________________________
. _________________________
Multiple Choice
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Identify the letter of the choice that best completes the statement or answers the question.
____
1. When a negatively charged object makes contact with a neutral object, the negative charge is shared between
the two objects, and the objects both become negatively charged. This is an example of
a. charging by friction
d. Coulomb’s law
b. charging by contact
e. charging by induction
c. induced charge separation
____
2. Two charged spheres are 15.00 cm apart. One sphere has a charge of
and the other sphere has a
charge of
. Assuming k =
, the electric force between the two spheres is
a.
d.
N
N
b.
e.
N
N
c.
N
____
3. Four charged spheres, A, D, P, and T are arranged as shown below. Sphere A has a charge of
C,
sphere D has a charge of
C, sphere P has a charge of
C, and sphere T has a charge of
C. Which two spheres exert the smallest force on each other?
a. A and D
d. P and D
b. A and T
e. P and T
c. A and P
____
4. Which of the following diagrams represents the field of force around a negative point charge?
a.
d.
b.
e.
c.
____
5. Which of the following diagrams most accurately depicts the field between two oppositely charged plates?
a.
d.
b.
e.
c.
____
____
____
____
6. Who determined the elementary charge?
a. Lenz
d. Einstein
b. Faraday
e. Berg
c. Millikan
7. The electric field intensity between two parallel plates is 300.0 N/C. The plates are connected to a battery
with an electric potential difference of 12.0 V. The separation of the plates is
a. 25.0 m
d. 4.0  10–7 m
b. 3600.0 m
e. 0.040 m
11
c. 2.3  10 m
8. The number of electrons that must be removed from a sphere to give it a charge of 9.2  10–5 C is
a. 1.7  1015
d. 8.3  105
b. 9.8  1013
e. 1.7  10–15
14
c. 5.8  10
9.
FM
The direction of the positively charged particle’s velocity according to the diagram above must be
a. to the left
b. to the right
c. upward
d. out of the page, perpendicular to the page
e. into the page, perpendicular to the page
____ 10. A electron of charge –1.6  10–19 C is moving east with a speed of 8.2  105 m/s, as it enters a magnetic field
of 1.5 T directed into the page. The magnitude and direction of the magnetic force acting on the proton is
a. 8.7  10–14 N [S]
d. 2.0  10–13 N [S]
–25
b. 2.9  10 N [N]
e. 2.9  10–25 N [S]
c. 2.0  10–13 N [N]
____ 11. A 50.0-cm straight conductor carries a current of 10.0 A through a uniform 0.55-T magnetic field. When the
angle between the current and the magnetic field is 80.0°, the magnitude of the force on the conductor is
a. 270 N
d. 2.7 N
b. 280 N
e. 2.8 N
c. 11 N
____ 12. A conductor is located between the poles of a horseshoe magnet. Current flows in the direction indicated by
the arrow on the diagram. (Hint: Point fingers from North to South in direction of field lines)
In which direction will the conductor move?
a. upward
d. right
b. left
e. out of the page
c. downward
____ 13. What is the current flowing through a 4.0 cm long solenoid with 150 turns and a magnetic field of 3.6  10–3
T in its core?
a. 2.2  100 A
d. 1.3  100 A
–1
b. 7.6  10 A
e. 4.8  102 A
–2
c. 2.2  10 A
____ 14. What factors would change the magnetic force in a solenoid.
a. Changing the turns
d. All of the above
b. Changing the current
c. Changing the core material
____ 15. Which of the following statements about the solenoid diagram below is incorrect?
a. The direction of the magnetic field is perpendicular to WX and YZ.
b. The direction of the magnetic field is parallel to XY.
c. The magnitude of the magnetic field along XY is B.
d. The magnitude of the magnetic field along ZW is B.
e. The net current flowing through the area WXYZ is NI.
____ 16. In the diagram below, a permanent magnet located above the loop is pushed downward through the loop of
wire.
Which of the following describes the induced current as viewed from above?
a. clockwise then counterclockwise
d. counterclockwise
b. clockwise
e. No current is induced.
c. counterclockwise then clockwise
Making Connections
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/2 1. Suggest two ways that Millikan’s experiment showed great scientific inquiry.
/3 2. Using several diagrams, explain the process of charging by induced separation. All you have is a positive rod, and
electroscope. Mention whether the charge on the leaves of the electroscope are permanent or temporary.
/5 3. Explain Faraday’s Law of Electromagnetic Induction and Lenz’s Law using the “4 domino model” as discussed in
class. Give one application (but don’t explain) where these law’s are used.
/4 4. Station 6 was a bell that was operated using a simple solenoid and 1.5V battery. Explain how this bell operates
using diagrams.
Problem
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/8 1. Two students, Emily and Stu rub their feet on a carpet thereby obtaining charges, Emily of charge +2.5  10–5
C and “Stu-Man-Chu” of charge –3.7  10–7 C. They stand 25.0 cm apart. Emily is to the left of Stu.
(a) Draw a diagram showing the charges and label a point Y that is 10.0 cm away from Stu, on the line
connecting the charge. (Field lines do not need to be drawn.)
(b) Calculate the electric field at point Y.
/8 2. Nathan Woodland is in the business of placing oil drops in electric fields and balancing them, much like Millikan.
Woody’s boss comes running into the room and scream, “I need you to balance this oil drop which has an
excess of 23 electrons immediately.” The mass of this oil drop is 1.72x10-26kg and the parallel plate
apparatus that Nathan is using has plates located 2.0mm apart.
a) Draw a FBD on the oil drop, and also show the parallel plate apparatus indicating which plate is on the
top and which is on the bottom.
b) Calculate the potential difference between the plates that makes this task possible.
/4 3. a) The magnitude of the magnetic field 0.50 m from a long, straight conductor is 2.73  10–3 T. Determine the
current flowing through the wire.
b) Use the right hand rule to determine the direction of the current flowing, if the magnetic field is out of the
page and the force on the conductor is North.
/8 4. Calculate the magintiude of the magnetic field at a point midway between two long, parallel wires that are 1.0m apart
and have currents of 10.0A and 20.0A respectively, if the currents are
a) In opposite directions.
b) In the same direction.
Bonus (try 1 for a chance at 2 marks)
1. Prove that 1 T which equals 1N/Am also equals 1kg/Cs
Unit 3 Electricity and Magnetism Summative
Answer Section
MODIFIED TRUE/FALSE
1. ANS:
LOC:
2. ANS:
LOC:
3. ANS:
T
REF: K/U
EG1.01
T
REF: K/U
EG1.02
F, square of the distance between the charges
OBJ: 7.1
OBJ: 7.2
REF: K/U
OBJ: 7.2
LOC: EG1.02
4. ANS: F, whereas the electric force can attract or repel
REF: K/U
OBJ: 7.2
LOC: EG1.02
5. ANS: F, positive charges and end on negative charges
REF: K/U
OBJ: 7.3
LOC: EG1.04
6. ANS: F, the electric force up cancels the gravitational force down
REF: K/U
OBJ: 7.5
7. ANS: F, directed into
LOC: EG1.04
REF:
8. ANS:
LOC:
9. ANS:
LOC: EG1.08
REF: K/U
OBJ: 8.3
LOC: EG1.04
REF: K/U
OBJ: 8.5
OBJ:
OBJ:
OBJ:
OBJ:
OBJ:
OBJ:
OBJ:
OBJ:
OBJ:
OBJ:
OBJ:
OBJ:
OBJ:
OBJ:
OBJ:
OBJ:
OBJ:
OBJ:
OBJ:
OBJ:
OBJ:
LOC:
LOC:
LOC:
LOC:
LOC:
LOC:
LOC:
LOC:
LOC:
LOC:
LOC:
LOC:
LOC:
LOC:
LOC:
LOC:
LOC:
LOC:
LOC:
LOC:
LOC:
K/U
T
EG1.08
F,
OBJ: 8.2
REF: K/U
10. ANS: T
LOC: EG1.01
OBJ: 8.4
MULTIPLE CHOICE
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
27.
28.
29.
30.
31.
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
B
D
A
B
C
B
E
E
E
C
E
D
D
E
C
B
C
A
C
D
A
REF:
REF:
REF:
REF:
REF:
REF:
REF:
REF:
REF:
REF:
REF:
REF:
REF:
REF:
REF:
REF:
REF:
REF:
REF:
REF:
REF:
K/U
C
C
C
K/U
K/U
K/U
C
C
C
K/U
C
C
C
K/U
C
C
C
C
K/U
K/U
7.1
7.2
7.2
7.2
7.3
7.3
7.3
7.4
7.5
7.5
8.2
8.2
8.3
8.3
8.3
8.4
8.4
8.4
8.4
8.4
8.5
COMPLETION
30. ANS: Newton’s law of universal gravitation
REF: K/U
OBJ: 7.2
31. ANS: attract, repel, attract
LOC: EG1.02
EG1.01
EG1.03
EG1.03
EG1.03
EG1.04
EG1.06
EG1.06
EG1.06
EG1.06
EG1.06
EG1.08
EG1.08
EG1.08
EG1.08
EG1.08
EG1.07
EG1.07
EG1.07
EG1.07
EG1.07
EG1.01
REF: K/U
OBJ: 7.2
32. ANS: terminal velocity
LOC: EG1.02
REF: K/U
33. ANS: solenoid
OBJ: 7.5
LOC: EG1.08
REF: K/U
34. ANS: parallel
OBJ: 8.1
LOC: EG1.01
REF: K/U
35. ANS: force field
OBJ: 8.2
LOC: EG1.08
REF: K/U
36. ANS: 90°
OBJ: 8.2
LOC: EG1.04
REF: K/U
37. ANS:
0°
180°
OBJ: 8.3
LOC: EG1.08
REF: K/U
38. ANS: larger
OBJ: 8.3
LOC: EG1.08
OBJ: 8.5
LOC: EG1.01
REF: K/U
MATCHING
39.
40.
41.
42.
ANS:
ANS:
ANS:
ANS:
C
A
E
B
REF:
REF:
REF:
REF:
C
C
C
C
OBJ:
OBJ:
OBJ:
OBJ:
7.4
7.4
7.4
7.4
LOC:
LOC:
LOC:
LOC:
EG1.01
EG1.01
EG1.01
EG1.01
43.
44.
45.
46.
47.
48.
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
B
A
D
E
C
F
REF:
REF:
REF:
REF:
REF:
REF:
C
C
C
C
C
C
OBJ:
OBJ:
OBJ:
OBJ:
OBJ:
OBJ:
8.4
8.4
8.4
8.2
8.2
8.1
LOC:
LOC:
LOC:
LOC:
LOC:
LOC:
EG1.01
EG1.01
EG1.01
EG1.01
EG1.01
EG1.01
SHORT ANSWER
49. ANS:
The difference between the electric potential at point B and the electric potential at point A is equal to the
work-per-unit-charge that would be required to move the positive charge q from point A to point B in the
electric field.
REF: K/U
OBJ: 7.4
LOC: EG1.05
50. ANS:
When a current is induced in a coil by a changing magnetic field, the electric current is in a direction such that
its own magnetic field opposes the change that produced it.
REF: K/U
PROBLEM
51. ANS:
(a)
OBJ: 8.5
LOC: EG1.01
(b)
q1 = 2.5  10–5 C
q2 = –3.7  10–7 C
r1 = 25.0 cm
r2 = 10.0 cm
r1 = 25.0 cm – 10.0 cm = 15.0 cm = 0.15 m
The net electric field is 1.0  107 N/C [right].
REF: C
52. ANS:
OBJ: 7.3
LOC: EG1.06
The magnitude of the magnetic field is 1.2  10–2 T.
REF: C
53. ANS:
r = 0.50 m
B = 2.73  10–3 T
I=?
OBJ: 8.3
LOC: EG1.08
The current flowing through the wire is 6.8  103 A.
REF: C
54. ANS:
I = 15.0 A
B = 9.4  10–6 T
r=?
OBJ: 8.4
LOC: EG2.02
The distance from the conductor is 3.2  10–1 m.
REF: C
OBJ: 8.4
55. ANS:
L = 6.5 cm = 0.065 m
N = 350
B = 1.6  10–2 T
I=?
LOC: EG2.02
The current flowing through the solenoid is 2.4 A.
REF: C
OBJ: 8.4
LOC: EG1.07