Question

A student touches an electroscope with her finger, and a second student then brings a charged plexiglass rod near the electroscope but does not touch it. The first student removes her finger from the electroscope before the second student removes the plexiglass. Meanwhile a third student touches a different electroscope with a charged PVC pipe. Are both electroscopes charged? If so, are they the same charge or different charges? Explain your reasoning. Feel free to include any drawings or diagrams

Answer 1

As the first student touches the electroscope with her finger, any excess charge present in the electroscope flows out of it and into the ground through the student, making it neutral. A plexiglass when rubbed, becomes positively charged. As this rod is brought near to the neutral electroscope, the free electrons in the electroscope are drawn towards the rod, whereas positive charges moves to the ground. As the first student removes her finger, the ground is removed and the electroscope becomes negatively charged due to excess electrons.

A pvc pipe, when rubbed, becomes negatively charged. If it is touched to the electroscope, negative charges from the pipe flows into the electroscope, making the electroscope negatively charged.

So both electroscopes become negatively charged.

we will consider electroscope as a conducting sphere for simplicity.