Fig. Shows an uncharged, insulated conductor AB, which is in contact with gold leaf electroscope C. A positively charged rod is brought near the end A. What charge is developed at A, B, C and D?Why?

When a positively charged rod is brought near the end A of an uncharged, insulated conductor AB that is in contact with a gold leaf electroscope C, an interesting phenomenon occurs due to the principles of electrostatics. Let’s break down what happens step by step.

Understanding Charge Distribution

Initially, the conductor AB is uncharged, meaning it has an equal number of positive and negative charges. When the positively charged rod approaches end A, it creates an electric field around it. This field influences the charges within the conductor.

Induction Process

As the positively charged rod comes closer, the free electrons in the conductor AB are attracted towards the rod. This movement of electrons causes the following:

• At Point A: Since electrons are moving towards A, it becomes negatively charged due to the accumulation of these electrons.
• At Point B: As electrons move towards A, point B loses some of its electrons, resulting in a positive charge at this end.

Effect on the Electroscope

Now, let’s consider the gold leaf electroscope C, which is in contact with the conductor AB. The charge distribution affects the electroscope as follows:

• At Point C: The electroscope will also become positively charged because it is connected to point B, which has lost electrons.
• At Point D: The leaves of the electroscope will diverge due to the positive charge, indicating that they are repelling each other. This occurs because like charges repel.

Summary of Charges Developed

To summarize the charges developed at each point:

• Point A: Negatively charged (due to electron accumulation).
• Point B: Positively charged (due to electron deficiency).
• Point C: Positively charged (influenced by point B).
• Point D: Positively charged (as part of the electroscope, leading to divergence of the leaves).

Why This Happens

This entire process is a result of electrostatic induction, where the presence of a charged object influences the distribution of charges in a nearby conductor without direct contact. The movement of electrons towards the positively charged rod and the resultant charge separation in the conductor and electroscope illustrate fundamental concepts in electrostatics.

In essence, the interaction between the charged rod and the conductor leads to a clear demonstration of how electric fields can influence charge distribution, ultimately affecting nearby objects like the gold leaf electroscope.