AP Physics 2 Unit 2 Progress Check D

An electron is released from rest at point PP in an electric field whose equipotential lines are shown in the figure. What is the kinetic energy of the electron when it reaches point QQ ? Ignore gravitational effects.

4eV0

A negatively charged ion is initially moving to the right toward a pair of parallel plates, along the straight line that is midway between the plates. One plate has a positive charge, and the other has a negative charge of equal magnitude. As the ion approaches the plates, it follows the path shown by the dashed line. Gravitational effects are negligible. Which of the following correctly ranks the magnitude of the electric force FF exerted on the ion by the field at the four labeled points?

(FC=FD)>FB>FA

In the figures, the center circle represents the cross section of a positively charged conducting sphere. Which of the figures shows properly labeled electric equipotential surfaces?

1v 1/2v 1/3v 1/4v

Four charged spheres are located at the positions indicated in the diagram. The magnitude of the charge on each sphere is the same. The two spheres on the right have a positive charge, and the two spheres on the left have a negative charge. Three points AA, BB, and CC are also indicated in the diagram. Students measure the electric potential as a function of position xx along the horizontal line through point CC. Their data is shown in the table. Position (cmcm)123567Potential (VV)−16−16−6.4−6.4−2.3−2.32.56.316 Which of the following is the best estimate of the magnitude of the electric field at point CC?

240N/C

A point charge of −q−q is located at (x,0)(x,0), and a point charge of +q+q is located at (−x,0)(−x,0), as shown. The magnitude of the electric field created by one of these point charges at the point (0,y)(0,y), which is a distance rr from each point charge, is EE. What is the magnitude and direction of the electric field created by both point charges at the point (0,y)(0,y) ?

2Exr positive xx-direction

An object with a charge of −1.0×10−6C−1.0×10−6C moves a distance of 0.1m0.1m parallel to an electric field. The object starts at a location where the electric potential is 10V10V and stops at a location where the electric potential is 100V100V . The average electric field between the two locations is most nearly

900NC

A uniform electric field of 1000N/C1000N/C is directed toward the right, as shown by the long arrows. A positron in the field has an initial velocity to the left at time t0t0 shown. At a later time t1t1 the positron is located 1m1m to the right of the position shown. What are the changes in the electric potential energy of the positron-field system and the kinetic energy of the positron between times t0t0 and t1t1 ?

Change in Electric Potential −1.6×10−16J Change in Kinetic Energy 1.6×10−16J

Four charged spheres are located at the positions indicated in the diagram. The magnitude of the charge on each sphere is the same. The two spheres on the right have a positive charge, and the two spheres on the left have a negative charge. Three points AA, BB, and CC are also indicated in the diagram. Which of the following correctly ranks the electric field at points AA, BB, and CC?

EC>EA>EB

Two spheres of mass MM and 2M2M are located a distance dd apart, as shown. A set of gravitational equipotential lines can be associated with the spheres. If the spheres are also charged, for which of the following pairs of charges will the electric equipotential lines have a shape and pattern most similar to the gravitational equipotential lines?

Left Sphere -Q Right Sphere -2Q

Four charged spheres are located at the positions indicated in the diagram. The magnitude of the charge on each sphere is the same. The two spheres on the right have a positive charge, and the two spheres on the left have a negative charge. Three points AA, BB, and CC are also indicated in the diagram. A small positive test charge is initially located at a point far to the right of the arrangement at x=+∞x=+∞ and y=4cmy=4cm, which is the same vertical height as point BB. The test charge can be moved horizontally from x=+∞x=+∞ to either x=8cmx=8cm or to x=0cmx=0cm. Which of the following indicates the final destination that would require more positive work to be done on the charge, and the reason more work done?

Moving the charge to x=8cmx=8cm would require more work. The final position is at a higher electric potential.

The figure shows a large positively charged metal plate and a small positively charged sphere on an insulating stick. Students measure the electric field above the plate when the sphere is in the position shown, which is above the center of the plate. They find the field is constant and uniform in a region above the center of the plate. Then they move the sphere very close to the center of the plate. One student says that the amount of work done to move the sphere is found by using W=qEdW=qEd, where qq is the charge on the sphere, EE is the uniform field that was measured, and dd is the distance that the sphere was moved. Is the student correct? Why or why not?

No, because moving the sphere closer to the plate affects the distribution of charge on the plate, so its electric field changes.

A particle with a small electric charge is moved in an electric field by an external force. When the particle is moved along an electric potential isoline, in what direction, if any, is the force exerted by the electric field on the particle?

Perpendicular to the direction of the particle's motion

A positively charged ion moves to the right between a pair of horizontal parallel plates along a straight line that is midway between the plates. One plate has a positive charge, and the other has a negative charge of equal magnitude. Gravitational effects are not negligible. Which of the following correctly ranks the total potential energy UU of the particle-fields system at the labeled points?

UA=UB=UC=UD

A negatively charged ion is initially moving to the right toward a pair of parallel plates, along the straight line that is midway between the plates. One plate has a positive charge, and the other has a negative charge of equal magnitude. As the ion approaches the plates, it follows the path shown by the dashed line. Gravitational effects are negligible. Which of the following correctly ranks the electric potential energy UU of the particle-field system at the labeled points?

UA>UB>UC>UD

In the figure, two dots represent the locations of Planets XX and YY . The lines are gravitational equipotentials, with an equal difference in potential between each set of adjacent lines. Which of the following correctly ranks the absolute value of the gravitational potential VV at the four labeled locations?

VM>(VL=VK)>VJ

A pair of plates has charges of equal magnitude and opposite sign, creating a uniform electric field of magnitude EE between them and away from their edges. A particle with positive charge qq is moved through a distance dd, from position AA to position BB , as shown in the diagram. Which of the following describes the force the field exerts on the particle and the work done by the field on the particle?

force qEqE to the right. work W=qEd

Two charged spheres, XX and YY, are held fixed at two vertices of a triangle, as shown. The direction of the electric field EE at the third vertex due to the two spheres is also shown. Which of the following best represents a closeup view of the equipotential lines near the third vertex of the triangle?

v1< v2 horzontal