A positive rod is placed to the left of sphere A, and the spheres are separated.

Question

An illustration of two spheres on rods touching each other labeled A and B and are neutral. There is a positively charged rod brought next to the sphere labeled A and it is negative. Sphere B has positive charges far from the rod.

Which best describes the spheres?

Sphere A is negative and sphere B is positive because protons from sphere A are attracted to the rod and move to sphere B.
Sphere A is negative and sphere B is positive because electrons from sphere B are attracted to the rod and move to sphere A.
Sphere A is positive and sphere B is negative because electrons from the rod move to sphere B and protons then move to sphere A.
Sphere A is positive and sphere B is negative because protons move from sphere B to the rod and also to sphere A.

Answer 1

To analyze the situation described, we need to understand the interactions of charges.

1. A positively charged rod is brought near sphere A.
2. Sphere A is initially neutral, meaning it has equal amounts of positive protons and negative electrons.
3. The presence of the positively charged rod induces a separation of charges within sphere A, attracting the negative electrons closer to the rod and repelling the positive protons away. This makes sphere A have an excess of negative charge on the side closer to the rod and a positive charge on the side farther from the rod.
4. Sphere B, which is also neutral, is affected by the field but remains neutral overall unless charged.

Now let's evaluate the answer choices provided:

• Sphere A is negative and sphere B is positive because protons from sphere A are attracted to the rod and move to sphere B.

  • This isn't correct; protons do not move through conductors in this situation.

• Sphere A is negative and sphere B is positive because electrons from sphere B are attracted to the rod and move to sphere A.

  • This is not correct; sphere B remains neutral, and the electrons move towards the positively charged rod instead.

• Sphere A is positive and sphere B is negative because electrons from the rod move to sphere B and protons then move to sphere A.

  • This choice suggests that electrons from the rod are transferred to sphere B, which isn't correct. Electrons from the rod do not move to sphere B in this setup.

• Sphere A is positive and sphere B is negative because protons move from sphere B to the rod and also to sphere A.

  • This isn't accurate either; protons do not move in this scenario.

In conclusion, none of the provided answer choices accurately describe the situation as presented. Sphere A becomes negatively charged due to the attraction of negative electrons towards the positively charged rod, while sphere B remains neutral. If the spheres are conductive and allowed to touch or if they were connected, the charges could redistribute, but as stated, one sphere does not gain a charge from the other in this circumstance based solely on the description provided.