1.

An electron moves from point i to point f, in the direction of a uniform electric field. During this placement:

 A. the work done by the field is positive and the potential energy of the electron-field system increases
 B. the work done by the field is negative and the potential energy of the electron-field system increases
 C. the work done by the field is positive and the potential energy of the electron-field system decreases
 D. the work done by the field is negative and the potential energy of the electron-field system decreases
 E. the work done by the field is positive and the potential energy of the electron-field system does not change

2. Three charges lie on the x axis: 1 × 10–8 C at x = 1 cm, 2 × 10–8 C at x = 2 cm, and 3 × 10–8 C at x = 3 cm. The potential energy of this arrangement, relative to the potential energy for infinite separation, is:
 A. 7.9 × 10–2 J
 B. 8.5 × 10–4 J
 C. 1.7 × 10–3 J
 D. 0.16 J
 E. zero

3. The potential difference between two points is 100 V. If 2 C is transported from one of these points to the other, the magnitude of the work done is:
 A. 200 J
 B. 100 J
 C. 50 J
 D. 100 V
 E. 2 J

4. A 5-cm radius conducting sphere is charged until the electric field just outside its surface is 2000 V/m. The electric potential of the sphere, relative to the potential far away, is:
 A. 0
 B. 5 V
 C. 100 V
 D. 4 × 104 V
 E. 8 × 105 V

5. In a certain region of space the electric potential increases uniformly from north to south and does not vary in any other direction. The electric field:
 A. points north and varies with position
 B. points north and does not vary with position
 C. points south and varies with position
 D. points south and does not vary with position
 E. points east and does not vary with position

6.

The diagram shows four pairs of large parallel conducting plates. The value of the electric potential is given for each plate. Rank the pairs according to the magnitude of the electric field between the plates, least to greatest.

 A. 1, 2, 3, 4
 B. 4, 3, 2, 1
 C. 2, 3, 1, 4
 D. 2, 4, 1, 3
 E. 3, 2, 4, 1

7.

Points R and T are each a distance d from each of two equal and opposite charges as shown. If k = 1/4p50, the work required to move a negative charge q from R to T is:

 A. zero
 B. kqQ/d2
 C. kqQ/d
 D.
 E. kQq/(2d)

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