# Chapter 26: Capacitance and Dielectrics

Now that you have developed an understanding of electric fields and electric potentials, you have the tools needed to understand a capacitor. A parallel-plate capacitor consists of two conducting sheets close enough together so that they can store equal and opposite charge with a potential difference between them. The amount of charge a parallel-plate capacitor stores at a particular voltage depends on its geometry and is characterized as its capacity or *capacitance* (measured in farads = 1 coulomb/volt). A common way to increase the capacitance of a capacitor is to put a dielectric (non-conductor) between the conducting plates. The charges in the dielectric are bound charges (not free to move away from a particular site within the material) in comparison with the free electrons of a conductor (that move in the presence of an electric field).

# Table of Contents

## Illustrations

- Illustration 26.1: Microscopic View of a Capacitor.
- Illustration 26.2: A Capacitor Connected to a Battery.
- Illustration 26.3: Capacitor with a Dielectric.
- Illustration 26.4: Microscopic View of Capacitors in Series and Parallel.

## Explorations

- Exploration 26.1: Energy.
- Exploration 26.2: Capacitors, Charge, and Electric Potential.
- Exploration 26.3: Conductors and Dielectrics.
- Exploration 26.4: Equivalent Capacitance.
- Exploration 26.5: Capacitance of Concentric Cylinders.

## Problems

- Problem 26.1: Capacitor dimensions (identify the correct graph).
- Problem 26.2: Describe the charge distribution and find the electric potential across a capacitor.
- Problem 26.3: Is this capacitor connected to a battery?
- Problem 26.4: Find the dielectric.
- Problem 26.5: Rank the value of the dielectrics.
- Problem 26.6: Rank the value of the dielectrics.
- Problem 26.7: Which capacitor with dielectric is connected to a battery?
- Problem 26.8: Find the value of the dielectric constant.
- Problem 26.9: Capacitors in parallel (microscopic view).
- Problem 26.10: Capacitors in series (microscopic view).
- Problem 26.11: Equivalent capacitance: what's wrong with this circuit?
- Problem 26.12: Calculate capacitance of concentric spheres.