Justin Geeslin

Eng Physics II - M 1:00

Experiment One – Electrostatics


  1. Introduction

This experiment attempts to demonstrate the effects of an electrical force on objects of differing charge. This is demonstrated in several ways in objects with multiple masses and characteristics. Also, an electroscope is used allowing for a clearer example of how and to where electrons flow.

  1. Procedure

For the first demonstration of static charge, scraps of paper will be attracted by a charged rod. Use the ebonite rod and charge it by rubbing the fur upon it. Then bring the paper and the rod closer together such that the rod is just hovering over the bits of paper. Physical contact should only occur due to the electrical forces between the rod and the paper. These forces should make the paper be attracted to and stick on the rod.

The next demonstration involves suspending a pith ball by a string in mid-air then using again the charged rod the move the ball. This is done by the charging the rod with fur or a similar material. Please note, at this point, it is important to discharge the ball by touching it with your hand. This is to ensure the ball itself is not charged initially. It will only be attracted if the ball is not charged. Once the rod is charged, bring it near the ball. The ball should be attracted. Once the ball makes contact, it should be violently repelled from the rod. This because once contact is made between a charged and not charged object the positive and negative charges in both objects are reconciled together forming two relatively neutrally charged objects. These two objects now having the same charge will repel each other.

Next, the charged rod will be used with an initially neutral electroscope. Again, for best results, it is important to touch the electroscope to give it a more negative charge. When the charged rod is brought near to the electroscope which now should be negatively charged, the charged should rush out of the electroscope toward the rod causing the leaves to collapse in on each other. Likewise, when the rod has no charge the leaves will be repelled from the rod and cause the leaves to expand. Sometimes a cause for error is to touch the side of the electroscope with the rod. This would cause inaccurate results because the leaves themselves would be attracted to the rod instead of being affected by the charge of the rod through the electroscope.


Questions

  1. Conductor will carry a charge and an insulator will not.

  2. Such repulsion is due the reconciliation of charges between the two objects. The positive charge from one object is shared across another object such that the charges of the two objects become neutral relative to each other. This means that the charges are the same and therefore the objects would become repelled by each other.

  3. The wall is neutral in a way that it contains both positive and negative charges. The charged balloon, like any charged object, would cause the charges within the wall to become polarized. This would allow the charges opposite of the balloon to surface and be attracted by the balloon. The wall and the balloon at this point become attracted to each other because of apparent opposite charges.

  4. The concept of Conversion of Charge means that electricity never leaves the system. Charge is only transferred never created or destroyed.