1. Electric Forces and Fields

2. F1→3 is more than twice as big as F2→3.
Three identical charges are lined up in a row. If we compare the electric force charge q1 exerts on charge q3 (F1 →3) to the force q2 exerts on charge q3 (F2→3)
F1→3 is twice as big as F2→3.
F1→3 is half as big as F2→3.
F1→3 is more than twice as big as F2→3.
F1→3 is less than half as big as F2→3.
F1→3 doesn’t affect q3 at all since q2 is in the way.
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3. Physics 131
10/17/11
In the figure are shown four arrangements of charge. Each charge has the same magnitude, but some are + and some are -. All distances are to the same scale. In which would the magnitude of the force felt by a positive test charge placed at P be the largest? A B C D
You can’t tell.
NEXUS/Physics Clicker Questions
Prof. E. F. Redish

4. Physics 122
4/1/11
In the figure each of the red charges are positive and have the same magnitude. In which of the diagrams would the magnitude of the force felt by a positive test charge placed at P be the largest?
Case 1
Case 2
Both are the same
You can’t tell
Physics 122

5. Two small objects each with a net charge of Q (positive) exert a force of magnitude F on each other. We replace one of the objects with another whose net charge is 4Q. The original magnitude of the force on the Q charge was F; what is the magnitude of the force on the Q now?
16F 4F F
F/4
other
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6. In the original state we assumed Q was positive
In the original state we assumed Q was positive. If the symbol Q were taken to have a negative value, how would the forces change compared to the original state?
They would stay the same
Both would reverse
Only the left force would reverse
Only the right force would reverse
Something else
NEXUS/Physics Clicker Questions

7. Physics 131
10/17/11
A test charge (labeled q) is placed in a situation in which it feels the electrical force from three other charges (of opposite sign to it) labeled A, B, and C. (The charges are on a uniform grid as shown and the positions are to scale.) Which of the following combinations of forces is the greatest?
There is not enough information to tell.
NEXUS/Physics Clicker Questions
Prof. E. F. Redish

8. Two identical conductors hang from nonconducting strings
Two identical conductors hang from nonconducting strings. They are given charges q1 = Q and q2 = 3Q. After charging, the two strings make angles of θ1 and θ2 with the vertical. How do the angles compare?
θ1 > θ2
θ1 < θ2
θ1 = θ2
You don’t have enough information to tell.

9. Physics 131
10/17/11
In each of the four cases shown below, a particle of charge +q is placed a distance d from a particle of charge +4q. The particles are then released simultaneously. The masses of the particles are indicated in the diagram. Rank the magnitude of the acceleration of the RIGHT HAND particle just after it is released.
Case 1
Case 2
Case 3
Case 4
Cases 1 & 2
Cases 1 & 3
Cases 2 & 4
Cases 3 & 4
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Prof. E. F. Redish

10. The electric field at a particular point in space
Prof. E. F. Redish
12/28/2017
The electric field at a particular point in space
Depends only on the magnitude of the test charge used to measure it.
Depends only on the sign of the test charge used to measure it.
Depends on both the sign and magnitude of the test charge used to measure it.
Does not depend on the test charge used to measure it.
None of the above.
NEXUS/Physics Clicker Questions
Physics 122

11. Physics 122
12/28/2017
A test charge, q, is a distance d from a charge Q as shown. It feels an electric field, E0. If q were replaced by a charge –3q, the electric field it feels would
Change to -3E0
Change to -E0/3
Not change
Change to 3E0
Change to E0/3
Something else
NEXUS/Physics Clicker Questions
Physics 122