The negative plate of a parallel plate capacitor is given a charge of -20*10^-8 C. Find the charge appearing on the four surfaces of the capacitor plates

To understand the distribution of charge on a parallel plate capacitor, let’s first clarify how capacitors work. A parallel plate capacitor consists of two conductive plates separated by an insulating material, known as a dielectric. When one plate is charged negatively, the other plate must acquire an equal amount of positive charge due to the principle of conservation of charge.

Charge Distribution in a Parallel Plate Capacitor

In your case, the negative plate of the capacitor has been given a charge of -20 x 10^-8 C. This means that the negative plate has an excess of electrons, leading to a net negative charge. According to the rules governing capacitors, the positive plate will respond to this charge.

Understanding Charge on the Plates

When the negative plate has a charge of -20 x 10^-8 C, the positive plate will have a charge of +20 x 10^-8 C. This is because the capacitor must maintain electrical neutrality in the system. Here’s how the charges appear on the surfaces of the plates:

• Negative Plate: The surface facing the positive plate will have a charge of -20 x 10^-8 C.
• Negative Plate (Opposite Surface): The surface facing away from the positive plate will have no charge, as it is not influenced by the electric field created by the positive plate.
• Positive Plate: The surface facing the negative plate will have a charge of +20 x 10^-8 C.
• Positive Plate (Opposite Surface): Similar to the negative plate, the surface facing away from the negative plate will also have no charge.

Visualizing the Charge Distribution

To visualize this, think of the plates as two parallel mirrors. The charge on one plate reflects an equal and opposite charge on the other plate. The electric field created between the plates is uniform, and the charges are concentrated on the surfaces facing each other. The outer surfaces of both plates remain neutral because they are not connected to any external circuit or charge source.

Summary of Charge on Surfaces

In summary, the charges on the surfaces of the capacitor plates are as follows:

• Negative Plate (facing positive plate): -20 x 10^-8 C
• Negative Plate (opposite surface): 0 C
• Positive Plate (facing negative plate): +20 x 10^-8 C
• Positive Plate (opposite surface): 0 C

This distribution ensures that the capacitor functions effectively, storing energy in the electric field created between the plates. Understanding this concept is crucial for grasping how capacitors operate in various electronic circuits.