Download Practice Quiz 2

Practice Quiz 2
Name_________________________
1) An electron and a positron are released simultaneously from rest and start to move towards each other
because of the attractive Coulomb force between them. (Note: A positron is the antiparticle of the electron,
being in all aspects identical to the electron except in the sign of its electrical charge. The charge of the
positron is +e, while that of the electron is -e.) They are initially separated by a distance d. The two
particles eventually collide. When they collide,
A) they are closer to the electron's initial position.
B) they are at the midpoint of their initial separation.
C) they are closer to the positron's initial position.
D) Not enough data is given to predict where they collide.
2) Figure above shows four Gaussian surfaces surrounding a distribution of charges. The Gaussian surface
(surfaces) that has (have) electric flux of +q/εo through it (them) is (are)
A) a.
B) b.
C) b and d.
D) c.
3) The units of electrical flux are
A) Nm2/C.
B) Nm/C2.
C) Nm/C.
D) N/C.
4) Two point charges of +7.00 µC and +10.0 µC are placed inside a cube of edge length 0.100 m. The net
electric flux due to these charges is given by
A) 0.340 × 106 Nm2/C
B) 0.450 × 106 Nm2/C
C) 1.92 × 106 Nm2/C
D) 3.80 × 106 Nm2/C
5. At what point is the charge per unit area greatest on the surface of an irregularly shaped conducting
solid?
a. where surface curves inward
b. where surface is flat
c. where curvature is least
d. where curvature is greatest
6) Three equal point charges of varying signs are placed on the corners of a square of side d as shown in
Figure above. Which of the arrows shown represents the direction of the net electric field at the center of
the square?
A) A
B) B
C) C
D) D
7) Three point charges of magnitudes +6.0 µC, -7.0 µC, and -13 µC are placed on the x-axis at x = 0 cm, x
= 40 cm, and x = 120 cm, respectively. What is the force on the -13 µC charge due to the other two
charges?
A) -0.55 N
B) 0.55 N
C) 0.79 N
D) -0.79 N
8. If a conductor is in electrostatic equilibrium near an electrical charge:
a. the total charge on the conductor must be zero.
b. the electric field inside the conductor must be zero.
c. any charges on the conductor must be uniformly distributed.
d. the sum of all forces between the conductor and the charge must be zero.
Answer B
9. An initially uncharged hollow metallic sphere with radius of 5 cm has a small object with a charge of
+10 µC carefully placed at the center of the sphere through a hole in the latter’s surface. What charge
resides inner surface of the sphere?
a. 4 000 µC
b. 10 µC
EB
c. +10 µC
d. zero
Answer B
E
E
C
+Q
A
–Q
10. Two charges, +Q and Q, are located two meters apart and there is a point along the line that is
equidistant from the two charges as indicated. Which vector best represents the direction of the electric
field at that point?
a. Vector EA
b. Vector EB
c. Vector EC
d. The electric field at that point is zero
Answer A