A student rubs a rubber rod with fur, producing a negative charge on the rod. The student then touches the rod to a hollow, neutral metal sphere that stands on an insulating plastic stand. This transfers negative charges from the rod to the sphere:

Question

Charged Rubber Rod
Metal Sphere
Insulating Plastic Stand
Which statement best predicts what will happen to the charge, and why?
It will quickly spread to the air around the sphere, because it will seek to occupy as large a volume of neutral matter as possible.
It will remain at the point of contact between the rod and the sphere, because resistance in the metal prevents the charges from easily moving.
It will distribute itself evenly over the surface of the sphere, because like charges repel and the sphere is a conductor.
It will slowly drift to the bottom of the sphere, because the charges rapidly attach to individual atoms, making
D. them slightly heavier than surrounding atoms.

Answer 1

The correct statement that best predicts what will happen to the charge on the hollow metal sphere after being touched by the negatively charged rubber rod is:

"It will distribute itself evenly over the surface of the sphere, because like charges repel and the sphere is a conductor."

When a charged object, like the rubber rod, comes into contact with a conductor (in this case, the metal sphere), the excess charge (negative charge from the rod) will redistribute itself over the surface of the conductor. This happens due to the repulsion between like charges. Since the sphere is hollow and a conductor, the negative charges will spread out evenly across the outer surface to minimize their potential energy, as charges repel each other. The nature of conductors allows charges to move freely, leading to an even distribution rather than remaining at the point of contact.

Answer 2

A student is investigating the distribution of charges in insulators. The student will place an aluminum metal can on top of a foam cup and touch the side of the foam cup with a negatively charged rod. The set up for the investigation is shown in the diagram.
CAN
What will MOST LIKELY happen to the electrons when the rod touches the foam cup?
The electrons will pass to the foam cup but will remain in a localized, positively charged area on the cup where
A. the rod was placed.
The electrons will pass to the foam cup but will remain in a localized, negatively charged area on the cup where
B. the rod was placed.
The electrons will pass from the foam cup to the aluminum can, and both the foam cup and the aluminum can
• с..
will become positively charged.
• D.
The electrons will pass from the foam cup to the aluminum can, and both the foam cup and the aluminum can will become negatively charged.

Answer 3

In this scenario, when the negatively charged rod touches the foam cup, the most likely outcome involves the behavior of electrons in relation to the insulating properties of the foam cup.

Since the foam cup is an insulator, the electrons from the negatively charged rod will not be able to move freely throughout the cup. Instead, when the rod touches the cup, some of the excess electrons from the rod will be transferred to the foam cup. However, because the foam cup is an insulator, the excess electrons will tend to stay localized rather than spreading out uniformly across the surface.

Thus, the correct answer would be:

B. The electrons will pass to the foam cup but will remain in a localized, negatively charged area on the cup where the rod was placed.

This means that the area of the cup in contact with the rod will become negatively charged due to the presence of the additional electrons, while the rest of the foam cup remains neutral. The insulating nature of the foam prevents the charges from redistributing evenly across the material. The aluminum can, being a conductor and not directly affected by the rod or the cup in this scenario, will not gain or lose electrons as a direct effect of this interaction.