Multiple Choice Test For FPSC, PPSC, NTS, CSS
And Various Exams
Subject Physics Chapter # 22 ELECTRIC FIELDS
1. An electric field is most directly related to:
A. the momentum of a test charge
B. the kinetic energy of a test charge
C. the potential energy of a test charge
D. the force acting on a test charge
E. the charge carried by a test charge
ans: D
2. As used in the definition of electric field, a “test charge”:
A. has zero charge
B. has charge of magnitude 1 C
C. has charge of magnitude 1 . 6 × 10-19 C
D. must be an electron
E. none of the above
ans: E
3. Experimenter A uses a test charge q0 and experimenter B uses a test charge -2q0 to measure
an electric field produced by stationary charges. A finds a field that is:
A. the same in both magnitude and direction as the field found by B
B. greater in magnitude than the field found by B
C. less in magnitude than the field found by B
D. opposite in direction to the field found by B
E. either greater or less than the field found by B, depending on the accelerations of the test charges
ans: A
4. The units of the electric field are:
A. N · C2
B. C/N
C. N
D. N/C2
E. C / m
ans: D
5. The units of the electric field are:
A. J/(C·m)
B. J/C
C. J·C
D. J/m
E. none of these
ans: A
6. Electric field lines:
A. are trajectories of a test charge
B. are vectors in the direction of the electric field
C. form closed loops
D. cross each other in the region between two point charges
E. are none of the above
ans: E
7. Two thin spherical shells, one with radius R and the other with radius 2R , surround an isolated
charged point particle. The ratio of the number of field lines through the larger sphere to the
number through the smaller is:
A. 1
B. 2
C. 4
D. 1 / 2
E. 1 / 4
ans: A
8. A certain physics textbook shows a region of space in which two electric field lines cross each
other. We conclude that:
A. at least two point charges are present
B. an electrical conductor is present
C. an insulator is present
D. the field points in two directions at the same place
E. the author made a mistake
ans: E
9. Choose the correct statement concerning electric field lines:
A. field lines may cross
B. field lines are close together where the field is large
C. field lines point away from a negatively charged particle
D. a charged point particle released from rest moves along a field line
E. none of these are correct
ans: B
10. Let k denote 1 / 4p 0 . The magnitude of the electric field at a distance r from an isolated point
particle with charge q is:
A. kq/r
B. kr/q
C. kq/r3
D. kq/r2
E. kq2 /r2
ans: D
11. The electric field at a distance of 10 cm from an isolated point particle with a charge of 2×10-9 C
is:
A. 1 . 8N / C
B. 180 N / C
C. 18 N / C
D. 1800 N / C
E. none of these
ans: D
12. An isolated charged point particle produces an electric field with magnitude E at a point 2 m
away from the charge. A point at which the field magnitude is E/ 4 is:
A. 1 m away from the particle
B. 0 . 5 m away from the particle
C. 2 m away from the particle
D. 4 m away from the particle
E. 8 m away from the particle
ans: D
13. An isolated charged point particle produces an electric field with magnitude E at a point 2 m
away. At a point 1 m from the particle the magnitude of the field is:
A. E
B. 2E
C. 4E
D. E/ 2
E. E/ 4
ans: C
14. Two point particles, with a charges of q1 and q2 , are placed a distance r apart. The electric field
is zero at a point P between the particles on the line segment connecting them. We conclude
that:
A. q1 and q2 must have the same magnitude and sign
B. P must be midway between the particles
C. q1 and q2 must have the same sign but may have different magnitudes
D. q1 and q2 must have equal magnitudes and opposite signs
E. q1 and q2 must have opposite signs and may have different magnitudes
ans: C
15. Two point particles, one with charge +8 × 10-9 C and the other with charge -2 × 10-9 C,
separated by 4 m. The electric field in N/C midway between them is:
A. 9 × 109
B. 13 , 500
C. 135 , 000
D. 36 × 10-9
E. 22 . 5
ans: E
16.Two charged point particles are located at two vertices of an equilateral triangle and the electric
field is zero at the third vertex. We conclude:
A. the two particles have charges with opposite signs and the same magnitude
B. the two particles have charges with opposite signs and different magnitudes
C. the two particles have identical charges
D. the two particles have charges with the same sign but different magnitudes
E. at least one other charged particle is present
ans: E
17. Two point particles, with the same charge, are located at two vertices of an equilateral triangle
A third charged particle is placed so the electric field at the third vertex is zero. The third particle must:
A. be on the perpendicular bisector of the line joining the first two charges
B. be on the line joining the first two charges
C. have the same charge as the first two particles
D. have charge of the same magnitude as the first two charges but its charge may have
different sign
E. be at the center of the triangle
ans: A
18. The electric field due to a uniform distribution of charge on a spherical shell is zero:
A. everywhere
B. nowhere
C. only at the center of the shell
D. only inside the shell
E. only outside the shell
ans: D
19. A charged particle is placed in an electric field that varies with location. No force is exerted
on this charge:
A. at locations where the electric field is zero
B. at locations where the electric field strength is 1 / (1 . 6 × 10-19 )N / C
C. if the particle is moving along a field line
D. if the particle is moving perpendicularly to a field line
E. if the field is caused by an equal amount of positive and negative charge
ans: A
20. The magnitude of the force of a 400-N/C electric field on a 0 . 02-C point charge is:
A. 8 . 0N
B. 8 × 10-5 N
C. 8 × 10-3 N
D. 0 . 08 N
E. 2 × 1011 N
ans: A
21. A 200-N/C electric field is in the positive x direction. The force on an electron in this field is:
A. 200 N in the positive x direction
B. 200 N in the negative x direction
C. 3 . 2 × 10-17 N in the positive x direction
D. 3 . 2 × 10-17 N in the negative x direction
E. 0
ans: D
22. An electron traveling north enters a region where the electric field is uniform and points north.
The electron:
A. speeds up
B. slows down
C. veers east
D. veers west
E. continues with the same speed in the same direction
ans: B
23. An electron traveling north enters a region where the electric field is uniform and points west
The electron:
A. speeds up
B. slows down
C. veers east
D. veers west
E. continues with the same speed in the same direction
ans: C
24. The force exerted by a uniform electric field on a dipole is:
A. parallel to the dipole moment
B. perpendicular to the dipole moment
C. parallel to the electric field
D. perpendicular to the electric field
E. none of the above
ans: E
25. An electric field exerts a torque a dipole only if:
A. the field is parallel to the dipole moment
B. the field is not parallel to the dipole moment
C. the field is perpendicular to the dipole moment
D. the field is not perpendicular to the dipole moment
E. the field is uniform
ans: B
26. The torque exerted by an electric field on a dipole is:
A. parallel to the field and perpendicular to the dipole moment
B. parallel to both the field and dipole moment
C. perpendicular to both the field and dipole moment
D. parallel to the dipole moment and perpendicular to the field
E. not related to the directions of the field and dipole moment
ans: C
27. A uniform electric field of 300 N / C makes an angle of 25 with the dipole moment of an electric
dipole. If the torque exerted by the field has a magnitude of 2 . 5 10- N m, the dipole moment must be:
A. 8 . 3 x 10- C m× 10 ·
B. 9 . 2 x 10- C m× 9 ·
C. 2 . 0 x 10- C m× 5 ·
D. 8 . 3 x 10- C m× 4 ·
E. 1 . 8 x 10- C m× 10
ans: C
28. When the dipole moment of a dipole in a uniform electric field rotates to become more nearly
aligned with the field:
A. the field does positive work and the potential energy increases
B. the field does positive work and the potential energy decreases
C. the field does negative work and the potential energy increases
D. the field does negative work and the potential energy decreases
E. the field does no work
ans: B
29. The purpose of Milliken’s oil drop experiment was to determine:
A. the mass of an electron
B. the charge of an electron
C. the ratio of charge to mass for an electron
D. the sign of the charge on an electron
E. viscosity
ans: B
30. A charged oil drop with a mass of 2 10- kg is held suspended by a downward electric field
of 300 N / C. The charge on the drop is:
A. +1 . 5 10- C× 6
B. 1 . 5 10- C × 6
C. +6 . 5 10- C× 6
D. 6 . 5 10- C
E. 0
ans: D
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