Chapter 6, Problem 2STP

To determine

To explain: the effect on the two leaves, if a negatively charged rod is brought close to a negatively charged electroscope, but not touching, the knob.

Explanation of Solution

Introduction:

A device that detects electric charge is known as an electroscope, it consists of two thin metal leaves attached to a metal rod. The electroscope, when not charged then leaves hang straight down whereas the electroscope, when charged then leaves are pushed apart.

In a negatively charged electroscope, the leaves have similar charges (negative), so they repel each other. When a negatively charged rod is brought close to the negatively charged electroscope, the leaves will move further apart. Negative charges from the rod will repel the negative charge on the electrode. As a result, the negative charges on the metal rod of the electroscope will travel down to the leaves. Since both leaves are already negatively charged, on gaining more negative charge, they will repel more. Hence, they move further apart.

Conclusion:

The two leaves will move further apart.