Propertie of Charges

Three identical conducting spheres, S1, S2, and S3, are supported by insulating thread, as shown above. Initially, sphere S1 has a net positive charge and the other two spheres are uncharged. Spheres S1 and S2 are brought into contact and then separated. Next, spheres S2 and S3 are brought into contact and then separated. Which of the following shows the signs of the final net charges on the spheres?

Conducting spheres 1 and 2 are initially uncharged, and sphere 1 is connected to ground. A rod carrying positive charge is brought near the right side of sphere 2. The ground is disconnected and then the rod is removed. Which of the following represents the resulting charge distribution on the two spheres?

Balloons 1 and 2 are tied to strings attached to a table and are attracted to each other, as shown in the figure. Balloon 1 has no net charge. Which of the following statements about the balloons are correct? Select two answers.