Ch 22

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

30. The magnitude of the force of a 400-N/C electric field on a 0.02-C point charge is:

A. 8.0N

5. The units of the electric field are:

A. J/(C·m)

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

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

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

The diagram shows a particle with positive charge Q and a particle with negative charge −Q. The electric field at point P on the perpendicular bisector of the line joining them is:

A. ↑

10. The diagram shows the electric field lines due to two charged parallel metal plates. We conclude that:

B. a proton at X would experience the same force if it were placed at Y

9. Choose the correct statement concerning electric field lines:

B. field lines are close together where the field is large

26. Positive charge +Q is uniformly distributed on the upper half a semicircular rod and negative charge −Q is uniformly distributed on the lower half. What is the direction of the electric field at point P, the center of the semicircle?

B. ↓

Positive charge +Q is uniformly distributed on the upper half a rod and negative charge −Q is uniformly distributed on the lower half. What is the direction of the electric field at point P, on the perpendicular bisector of the rod?

B. ↓

16. An isolated charged point particle produces an electric field with magnitude E at a point 2m away. At a point 1m from the particle the magnitude of the field is:

C. 4E

The diagrams below depict four different charge distributions. The charge particles are all the same distance from the origin. The electric field at the origin:

C. is zero for situation 4

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:

C. q1 and q2 must have the same sign but may have different magnitudes

The diagram shows two identical particles, each with positive charge Q. The electric field at point P on the perpendicular bisector of the line joining them is:

C. →

14. The electric field at a distance of 10 cm from an isolated point particle with a charge of 2×10−9 C is:

D. 1800N/C

15. An isolated charged point particle produces an electric field with magnitude E at a point 2m away from the charge. A point at which the field magnitude is E/4 is:

D. 4m away from the particle

4. The units of the electric field are:

D. N/C

The diagram shows the electric field lines in a region of space containing two small charged spheres (Y and Z). Then:

D. Y is positive and Z is negative

11. Let k denote 1/4πe0. The magnitude of the electric field at a distance r from an isolated point particle with charge q is:

D. k*q/r^2

The electric field due to a uniform distribution of charge on a spherical shell is zero:

D. only inside the shell

12. The diagram shows the electric field lines in a region of space containing two small charged spheres (Y and Z). Then:

D. the electric field is not zero anywhere (except infinitely far from the spheres)

1. An electric field is most directly related to:

D. the force acting on a test charge

Positive charge Q is uniformly distributed on a semicircular rod. What is the direction of the electric field at point P, the center of the semicircle?

D. →

Two point particles, one with charge +8 × 10−9 C and the other with charge −2 × 10−9 C, are separated by 4m. The electric field in N/C midway between them is:

E. 22.5

6. Electric field lines:

E. are none of the above

23. 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:

E. at least one other charged particle is present

2. As used in the definition of electric field, a "test charge":

E. none of the above

8. A certain physics textbook shows a region of space in which two electric field lines cross each other. We conclude that:

E. the author made a mistake

17. Two protons (p1 and p2) are on the x axis, as shown below. The directions of the electric field at points 1, 2, and 3, respectively, are:

E. ←−, ←−, −→