91Ó°ÊÓ

Electrostatic force is a fundamental force that acts between charges. It is described by Coulomb's Law, which calculates the force between two point charges. If you have charges like the ones from the exercise, where one charge is positive and the other is negative, the electrostatic force between them can be attractive.

Using Coulomb's Law, the force magnitude is given by: \( F = k \frac{|q_1q_2|}{r^2} \) where:

• \(F\) is the force between charges,
• \(k\) is Coulomb's constant \(8.99 \times 10^9 \mathrm{N \cdot m^2/C^2}\),
• \(q_1\) and \(q_2\) are the amounts of the charges,
• \(r\) is the distance between the centers of the charges.

With opposite charges like the ones in the exercise, the force \(F_1\) is attractive. Understanding this concept is crucial, because it explains why charged objects can exert forces over a distance.

Charge neutralization happens when two charged bodies come to the point where the total charge is balanced or zero. In the exercise, this is demonstrated when the two spheres, initially having opposite charges of \(100 \, \mu \text{C}\) and \(-100 \, \mu \text{C}\), are connected by a metallic wire.

The connection allows the charges to balance out since charges will flow to equalize potential. The total charge becomes zero because:\[ Q_\text{total} = 100 \, \mu \text{C} + (-100 \, \mu \text{C}) = 0 \]This leads to both spheres being uncharged after removing the wire. Consequently, the electrostatic force, which depends on the presence of charges, becomes nonexistent, which is why the force \(F_2\) equals zero after charge neutralization has occurred.

When a metallic conductor is introduced between charged objects, it allows for the free flow of charges. Metals are good conductors due to a sea of free electrons that can move easily. This property is utilized in the exercise when the spheres are connected by a metallic wire.

The interaction ensures that the charges redistribute themselves until there is no potential difference between the spheres. Essentially, this metallic conductor acts as a bridge for charge flow, achieving equilibrium. This is how charge neutralization occurs, as outlined in the previous section.

Once the wire is removed, it doesn't reintroduce charges; it merely ensures the charges have had a chance to disperse and equalize. This lack of residual charge explains why, once the wire is disconnected, the spheres exert no electrostatic force on each other, resulting in \(F_2\) being zero.