Three objects are brought close to one another, two at a time. When objects A and B are brought together, they attract. When objects B and C are brought together, they repel. Which of the following are necessarily true? (a) Objects A and C possess charges of the same sign. (b) Objects A and C possess charges of opposite sign. (c) All three objects possess charges of the same sign. (d) One object is neutral. (e) Additional experiments must be performed to determine information about the charges on the objects.

A common demonstration involves charging a rubber balloon, which is an insulator, by rubbing it on your hair and then touching the balloon to a ceiling or wall, which is also an insulator. Because of the electrical attraction between the charged balloon and the neutral wall, the balloon sticks to the wall. Imagine now that we have two infinitely large, flat sheets of insulating material. One is charged, and the other is neutral. If these sheets are brought into contact, does an attractive force exist between them as there was for the balloon and the wall?

What happens when a charged insulator is placed near an uncharged metallic object? (a) They repel each other. (b) They attract each other. (c) They may attract or repel each other, depending on whether the charge on the insulator is positive or negative. (d) They exert no electrostatic force on each other. (e) The charged insulator always spontaneously discharges.

Two small identical conducting spheres are placed with their centers 0.30 m apart. One is given a charge of 12 109 C, the other a charge of 18 109 C. (a) Find the electrostatic force exerted on one sphere by the other. (b) The spheres are connected by a conducting wire. Find the electrostatic force between the two after equilibrium is reached, where both spheres have the same charge.

A positive charge q1 = 2.70 C on a frictionless horizontal surface is attached to a spring of force constant k as in Figure P15.12. When a charge of q2 = 8.60 C is placed 9.50 cm away from the positive charge, the spring stretches by 5.00 mm, reducing the distance between charges to d = 9.00 cm. Find the value of k.

Calculate the magnitude and direction of the Coulomb force on each of the three charges shown in Figure P15.10.

Calculate the magnitude and direction of the Coulomb force on each of the three charges shown in Figure P15.10.

Using the symmetry of the arrangement, determine the direction of the force on q in the figure below, given that qa=qb=+7.50C and qc = qd = 7.50C. (b) Calculate the magnitude of the force on the charge q, given that the square is 10.0 cm on a side and q = 2.00 C.

Object A has a charge of +2 C, and object B has a charge of +6 C. Which statement is true? (a) FAB = 3FBA (b) FAB = FBA (c) 3FAB = FBA

A very small ball has a mass of 5.00 103 kg and a charge of 4.00 C. What magnitude electric field directed upward will balance the weight of the ball so that the ball is suspended motionless above the ground? (a) 8.21 102 N/C (b) 1.22 104 N/C (c) 2.00 102 N/C (d) 5.11 106 N/C (e) 3.72 103 N/C