Inductive Charging of an Electroscope

Introduction

• Demonstration of how to inductively charge an electroscope.
• Objective: Make the foils remain repelled even after removing the charged object.

Basic Concepts

• Uncharged Electroscope: Equal number of positive and negative charges.
  • Charges are balanced (neutral).
• Charged Object Influence: A negatively charged object near the terminal pushes negative charges to the foils, causing repulsion.

Traditional Process

• Charge object near electroscope => Foils repel.
• Remove charge object => Foils no longer repel.

Inductive Charging Process

1. Initial Setup

   • Begin with balanced charges.
   • Introduce negatively charged object near terminal.

2. Grounding

   • Touch terminal with finger while the charged object is near.
   • Creates an escape path for negative charges into the body (grounding).

3. Charging by Induction

   • Negative charges are repelled to the finger and away.
   • Terminal becomes more positively charged.
   • Negative charges return to the terminal from the foils.
   • Foils stop repelling as they lose extra negative charges.

4. After Effects

   • Remove finger, then remove charged object.
   • Foils now repel each other due to remaining positive charges.

Advanced Concepts

• Positive Object Influence:
  • Using a positively charged object can repel remaining negative charges to the foils.
  • This can increase the repulsion of the foils.

Summary of Demonstration

• Demonstrated charging an electroscope with a negatively charged object and grounding.
• Showed that the electroscope can remain positively charged, keeping foils repelled even without the charged object.
• Notes on protons: Positive charges (protons) do not move during this process; only electrons move.

Conclusion

• Induction method allows the electroscope to remain charged without the presence of a charged object.
• Similar results can be achieved with a positively charged object.
• This process highlights the principle that like charges repel, while unlike charges attract.

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Key Takeaways

• Understand the balance of charges in an electroscope.
• Learn the role of grounding in charge induction.
• Recognize how different charged objects affect the electroscope.