Tema 01 - A Carga Elétrica e o Spin | Experimentos - Lei de Coulomb II

Summary

This simple experiment demonstrates the concept of static electricity. Using straws, a graduated scale, a pin, paper towels, and a bottle, the straws are electrified through friction. The repulsive forces between the two similarly charged straws are observed until they align horizontally. By measuring the distance between the straws and applying Coulomb's law, the electric charge on each straw can be determined. The experiment also calculates how many electrons are transferred between the straw and the towel, providing a hands-on way to estimate electric charge and understand electrostatic forces.

Takeaways

• 😀 The experiment involves using straws, a graduated scale, a pin, paper towels, and a bottle as supports.
• 😀 The first step is to electrify a straw by rubbing it with paper towels and checking if it attracts objects, indicating it has an electric charge.
• 😀 Another straw is suspended as a pendulum, and when both straws have the same type of charge, they will repel each other.
• 😀 The repulsion between the two straws continues until the pendulum reaches a horizontal position, where the electrostatic repulsion balances the weight of the straw.
• 😀 The electrostatic force in this situation is balanced by the gravitational force (weight) of the straw, allowing us to determine the charge on each straw.
• 😀 Using the mass of the straws and the distance between them, along with the Coulomb's law equation, the charge on each straw can be calculated.
• 😀 The number of electrons transferred between the paper towel and the straw can also be determined through Coulomb's law.
• 😀 The experiment provides a simple way to estimate the amount of charge on an electrified straw.
• 😀 The force of repulsion between the straws is directly related to their charges and the distance between them.
• 😀 The charge value (q) is expressed in coulombs, with the mass in kilograms and the distance in meters, and Coulomb's constant (9 x 10^9 N·m²/C²) is used for calculations.

Q & A

What materials are used in the experiment described in the transcript?

The materials used include straws, a graduated scale, a pin, paper towel, and a bottle as support.

How is the straw electrified in the experiment?

The straw is electrified by rubbing it with paper towel, generating static charge through friction.

What is the method for checking if the straw is electrified?

To check if the straw is electrified, you can bring your hand close to it and observe if there is an attraction.

What happens when two similarly electrified straws are brought together?

When two straws, both electrified with the same type of charge, are brought together, they repel each other.

What is the condition when the pendulum straw reaches the horizontal position?

When the pendulum straw reaches the horizontal position, the electrostatic repulsive force almost balances out with the weight of the straw.

How can the charge on each straw be determined in the experiment?

The charge on each straw can be determined by measuring the distance between them, using the Coulomb equation, along with the mass of the straw.

What is the Coulomb equation used for in this experiment?

The Coulomb equation is used to calculate the electrostatic force between the charges on the straws, which helps determine the value of the charge on each straw.

What can be calculated using Coulomb’s law in this experiment?

Using Coulomb’s law, the amount of charge (Q) on each straw can be calculated, and also the number of electrons transferred during the electrification process.

What is the significance of the value 9 x 10^9 in the experiment?

The value 9 x 10^9 is the constant used in Coulomb’s law, representing the electrostatic constant (k), in units of Newton-meters squared per coulomb squared.

How are the charges of the straws expressed in the experiment?

The charges of the straws are expressed in coulombs (C), while the mass is in kilograms and the distance in meters.