# Parallel Plate Capacitor: Potential Difference *vs.* Spacing

Recommended for High School through College.

## Introduction

A capacitor is *defined* as any two conductors, separated by an insulator where each conductor carries a net excess charge that is equal in magnitude and opposite in sign. Its capacitance, *C*, is defined as

where *Q* is the magnitude of the excess charge on each conductor and *V* is the voltage (or potential difference) across the plates.

We can use Gaussâ€™ Law to analyze a parallel plate capacitor if we assume that most of the electric field lines are perpendicular to the plates. According to Gauss, if air is the insulator, the capacitance, *C*, is related to the area of the plates, *A*, and the spacing between them, *d*, by the equation

ε_{0} is known as the electric constant (or permittivity).

## Objectives

In this activity, you will

- Explore how the voltage (a.k.a. potential difference) across the plates varies as the distance between the charged plates increases.

## Software for Experiment

This experiment uses Logger *Pro* software for video analysis. The video for analysis is included with the lab book.