Download Quiz 09-1 Electrostatics

AP Physics
Mrs. Tsarevsky
Name_____________________
ELECTROSTATICS
Quiz 9-1
____ 1. Two uncharged conducting spheres, A and B, are suspended from insulating threads so
that they touch each other. While a negatively charged rod is held near, but not touching
sphere A, the two spheres are separated. How will the spheres be charged, if at all?
a)
b)
c)
d)
e)
Sphere A
0
0
+
Sphere B
+
+
0
0
-
____ 2. A conducting sphere has a net charge of 4.8  1017 C. What is the approximate
number of excess electrons on the sphere?
a) 100 b) 200 c) 300 d) 400 e) 500
____ 3. Complete the following statement: When a glass rod is rubbed with silk cloth, the rod
becomes positively charged as
a) positive charges are transferred from the silk to the rod.
b) negative charges are transferred from the rod to the silk.
c) positive charges are created on the surface of the rod.
d) negative charges are transferred from the silk to the rod.
e) positive charges are transferred from the rod to the silk.
____ 4. A charged conductor is brought near an uncharged insulator. Which one of the following
statements is true?
a) Both objects will repel each other.
b) Both objects will attract each other.
c) Neither object exerts an electrical force on the other.
d) The objects will repel each other only if the conductor has a negative charge.
e) The objects will attract each other only if the conductor has a positive charge.
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____5.
Three charged particles A, B, and C are located near one another. Both the
magnitude and direction of the force that particle A exerts on particle B is independent of
a) the sign of charge B.
d) the distance between A and B.
b) the sign of charge A.
e) the magnitude of the charge on B.
c) the distance between C and B.
____ 6. Two uncharged, conducting spheres, A and B, are held at rest on insulating stands and are
in contact. A positively charged rod is brought near sphere A as suggested in the figure.
While the rod is in place, the two spheres are separated. How will the spheres be
charged, if at all?
a)
b)
c)
d)
e)
Sphere A
positive
positive
negative
negative
zero
Sphere B
positive
negative
positive
negative
zero
____ 7. Consider three identical metal spheres, A, B, and C. Sphere A carries a charge of 2.0
µC; sphere B carries a charge of 6.0 µC; and sphere C carries a charge of +5.0 µC.
Spheres A and B are touched together and then separated. Spheres B and C are then
touched and separated. Does sphere C end up with an excess or a deficiency of electrons
and how many electrons is it?
a) deficiency, 3.12  1013
d) deficiency, 6.24  1012
13
b) excess, 3.12  10
e) deficiency, 3.74  1012
c) excess, 1.87  1013
____ 8. Four point charges, each of the same magnitude, with varying signs are arranged at the
corners of a square as shown. Which of the arrows labeled A, B, C, and D gives the
correct direction of the net force that acts on the charge at the upper right corner?
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a) A b) B
c) C d) D
e) The net force on that charge is zero.
____ 9. A charge Q exerts a 12 N force on another charge q. If the distance between the charges
is doubled, what is the magnitude of the force exerted on Q by q?
a) 3 N b) 6 N c) 24 N d) 36 N e) 48 N
____ 10. Four point charges are held fixed at the corners of a square as shown in the figure.
Which of the five arrows shown below most accurately shows the direction of the net
force on the charge Q due to the presence of the three other charges?
a)
b)
c)
d)
e)
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____ 11. At which point (or points) is the electric field zero N/C for the two point charges shown
on the x axis?
a)
b)
c)
d)
The electric field is never zero in the vicinity of these charges.
The electric field is zero somewhere on the x axis to the left of the +4q charge.
The electric field is zero somewhere on the x axis to the right of the 2q charge.
The electric field is zero somewhere on the x axis between the two charges, but this
point is nearer to the 2q charge.
e) The electric field is zero at two points along the x axis; one such point is to the right
of the 2q charge and the other is to the left of the +4q charge.
____ 12. Four point charges are placed at the corners of a square as shown in the figure. Each side
of the square has length 2.0 m. Determine the magnitude of the electric field at the point
P, the center of the square.
a) 2.0  106 N/C
b) 3.0  106 N/C
c) 9.0  103 N/C
d) 1.8  104 N/C
e) 2.7  104 N/C
____ 13. The figure shows the electric field lines in the vicinity of two point charges.
Which one of the following statements concerning this situation is true?
a)
b)
c)
d)
e)
q1 is negative and q2 is positive.
The magnitude of the ratio (q2/ q1) is 0.70.
Both q1and q2 have the same sign of charge.
The magnitude of the electric field is the same everywhere.
The electric field is strongest midway between the charges.
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____ 14. Three identical point charges, Q, are placed at the vertices of an equilateral triangle as
shown in the figure. The length of each side of the triangle is d. Determine the
magnitude and direction of the total electrostatic force on the charge at the top of the
triangle.
a)
Q2 3
, directed upward
4 0 d 2
b)
Q2 3
, directed downward
4 0 d 2
c)
Q2
, directed upward
2 0 d 2
d)
Q2
, directed downward
2 0 d 2
e) zero
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Answer Key
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
e
c
b
b
c
d
c
b
a
e
c
d
b
a
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