Question

An electroscope initially has a net negative charge. Why do the foils come together and stay together when a human hand touches the electroscope?

Answer 1

The foils of the electroscope come together and stay together when a human hand touches it because charge is transferred from the hand to the electroscope, reducing its net negative charge.

Step-by-step explanation:

When a human hand touches the electroscope, the foils come together and stay together because charge is transferred from the hand to the electroscope.

The electroscope can initially have a net negative charge, which means it has an excess of negative charge. When the hand touches the electroscope, some of the negative charge from the hand is transferred to the electroscope. This reduces the net negative charge on the electroscope, causing the foils to come together and stay together due to the absence of repulsive forces.

This happens because the human body can conduct electricity and allows charge to flow from the hand to the electroscope, equalizing the charges and causing the foils to collapse.

Answer 2

When a negatively charged electroscope is touched by a hand, grounding occurs, allowing excess electrons to flow to the earth, resulting in the foil leaves losing their excess charge and coming together.

Step-by-step explanation:

An electroscope with a net negative charge will have its foils repel each other because like charges repel. However, when a person touches the electroscope, the negative charge is grounded. The grounding process allows excess electrons to flow away into the earth, causing the previously repelling foil leaves to lose their excess negative charge and come together. If the hand is removed, the electroscope will remain neutral because it has the same amount of positive and negative charges; therefore, the leaves will stay together rather than repelling each other due to like charges.