Page 840 - College Physics For AP Courses

828
Chapter 18 | Electric Charge and Electric Field
a. b.
Find the ratio of the electrostatic force to the gravitational force between two electrons.
Will this ratio change if the two electrons are replaced by protons? If yes, find the new ratio.
18.5 Electric Field: Concept of a Field Revisited
31. Two particles with charges +2q and +q are separated by a distance r. The +2q particle has an electric field E at distance r and exerts a force F on the +q particle. Use this information to answer questions 31–32.
What is the electric field of the +q particle at the same distance and what force does it exert on the +2q particle?
a. E/2, F/2
b. E, F/2
c. E/2, F
d. E,F
Figure 18.65 An electric dipole (with +2q and –2q as the two charges) is shown in the figure above. A third charge, −q is placed equidistant from the dipole charges. What will be the direction of the net force on the third charge?
a. →
b. ←
c. ↓
d. ↑
32. When the +q particle is replaced by a +3q particle, what 39. will be the electric field and force from the +2q particle
experienced by the +3q particle?
a. E/3, 3F
b. E, 3F
c. E/3, F
d. E,F
33. The direction of the electric field of a negative charge is
a. inward for both positive and negative charges.
b. outward for both positive and negative charges.
c. inward for other positive charges and outward for other
negative charges.
d. outward for other positive charges and inward for other
negative charges.
34. The force responsible for holding an atom together is a. frictional
b. electric
c. gravitational
d. magnetic
35. When a positively charged particle exerts an inward force on another particle P, what will be the charge of P?
a. positive
b. negative
c. neutral
d. cannot be determined
36. Find the force exerted due to a particle having a charge of 3.2×10−19 C on another identical particle 5 cm away.
37. Suppose that the force exerted on an electron is
5.6×10−17 N, directed to the east.
a. Find the magnitude of the electric field that exerts the
force.
b. What will be the direction of the electric field?
c. If the electron is replaced by a proton, what will be the
magnitude of force exerted?
d. What will be the direction of force on the proton?
18.6 Electric Field Lines: Multiple Charges
38.
Figure 18.66
Four objects, each with charge +q, are held fixed on a square with sides of length d, as shown in the figure. Objects X and Z are at the midpoints of the sides of the square. The electrostatic force exerted by object W on object X is F. Use this information to answer questions 39–40.
What is the magnitude of force exerted by object W on Z?
a. F/7 b. F/5 c. F/3 d. F/2
40. What is the magnitude of the net force exerted on object X by objects W, Y, and Z?
a. F/4
b. F/2
c. 9F/4
d. 3F
41.
This OpenStax book is available for free at http://cnx.org/content/col11844/1.14