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

Summary

This experiment demonstrates the principles of electrostatics, focusing on Coulomb's Law. By using Styrofoam spheres, a PVC plate, and an electrophorus, the video shows how charged objects repel each other and how the force of repulsion is influenced by the distance between the objects. As the distance between the spheres decreases, the repulsive force increases, following an inverse square law. The experiment also explores how charges redistribute when a neutral sphere comes into contact with a charged one, ultimately leading to the discovery of Coulomb's Law, which defines the relationship between electric force, charge, and distance.

Takeaways

• 😀 The experiment involves styrofoam spheres painted with conductive paint, insulated with drinking straws, and a torsion pendulum with a second identical sphere.
• 😀 A PVC plate is initially rubbed to electrify it, and a pizza-shaped electrophorus is charged by induction before being placed near the styrofoam spheres.
• 😀 When the charged pizza-shaped electrophorus touches the styrofoam spheres, they become electrically charged by contact.
• 😀 The styrofoam spheres repel each other, indicating they have acquired the same type of charge.
• 😀 The repulsion force between the spheres can be determined by the angle of torsion of the wire holding the pendulum, which is calibrated beforehand.
• 😀 Decreasing the distance between the charged spheres increases the repulsion force, confirming that this force is inversely proportional to the square of the distance.
• 😀 If the distance between the charged spheres is halved, the repulsion force increases four times.
• 😀 If a third neutral (uncharged) sphere is brought into contact with one of the charged spheres, the charges distribute equally between the two spheres.
• 😀 After the third neutral sphere touches, each sphere ends up with half of the original charge, and the repulsion force decreases to half of its initial value.
• 😀 This experiment led to the development of Coulomb's law, which states that the force between two charged particles is proportional to the product of their charges and inversely proportional to the square of the distance between them.

Q & A

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

The experiment uses Styrofoam spheres painted with conductive paint, straws from soft drinks for insulation, a torsion pendulum made with another identical sphere, an electrophorus shaped like a pizza, and a PVC ceiling tile.

What is the first step in the experiment?

The first step is to rub the PVC plate to electrify it.

How is the pizza-shaped electrophorus charged in the experiment?

The pizza-shaped electrophorus is charged by induction and then is brought into contact with the Styrofoam spheres, charging them by contact.

What happens to the Styrofoam spheres after they are electrified?

The Styrofoam spheres repel each other after becoming electrified because they acquire charges of the same sign.

How can the repulsive force between the spheres be determined?

The repulsive force can be determined by measuring the angle of torsion of the wire holding the pendulum, which has been calibrated beforehand.

What happens when the distance between the charged spheres is reduced?

When the distance between the charged spheres is reduced, the repulsive force increases.

How does the repulsive force change with respect to the distance between the spheres?

The repulsive force increases with the inverse square of the distance. For example, if the distance is halved, the force increases four times.

What happens when a third neutral sphere is brought into contact with one of the charged spheres?

When a third neutral sphere touches one of the charged spheres, the charges distribute equally between the two spheres, and each sphere ends up with half of the initial charge.

What is the effect on the repulsive force when the neutral sphere touches a charged sphere?

When the neutral sphere touches a charged sphere, the repulsive force decreases and becomes half of its initial value.

How did Coulomb develop his famous equation, the law of Coulomb?

Coulomb developed his law based on experiments like the one described, where he observed the relationship between the force of repulsion, the product of charges, and the inverse square of the distance between them.