# Capacitors

## Overview

Welcome to the course material on Capacitors in General Physics. Capacitors are important components used in various electrical circuits for storing and releasing electric charge. In this course, we will delve into the different aspects of capacitors, ranging from their types and functions to the energy they store.

Firstly, it is crucial to understand the types and functions of capacitors. Capacitors come in various forms such as ceramic, electrolytic, and film capacitors, each serving specific functions in electronic circuits. They are commonly used to filter out noise, store energy, and regulate voltage levels in electrical systems.

One of the fundamental structures of capacitors is the parallel plate capacitor. This configuration consists of two parallel plates separated by a dielectric material. As the voltage across the plates increases, it leads to the accumulation of charge, thus establishing an electric field between the plates.

The capacitance of a capacitor is a key parameter that defines its ability to store charge. The relationship between capacitance, area, separation of plates, and the medium between the plates is given by the formula C = EA/d, where C is the capacitance, E is the permittivity of the medium, A is the area of the plates, and d is the separation distance.

When capacitors are connected in series or parallel, their overall capacitance changes based on the configuration. Capacitors in series have an effective capacitance given by the reciprocal of the sum of the reciprocals of individual capacitances. On the other hand, capacitors in parallel have a total capacitance equal to the sum of individual capacitances.

Furthermore, the energy stored in a capacitor is a crucial aspect to consider in electronic circuits. The energy stored in a capacitor is given by the formula E = 0.5CV^2, where E is the energy stored, C is the capacitance, and V is the voltage across the capacitor.

Throughout this course, we will explore the uses of capacitors, analyze parallel plate capacitors, determine capacitance, investigate factors affecting capacitance, solve problems involving capacitor arrangements, and calculate the energy stored in capacitors. Capacitors play a vital role in modern electronics, making it essential to grasp their principles and applications.

## Objectives

1. Determine the Energy Stored in Capacitors
2. Analyse Parallel Plate Capacitors
3. Analyse the Factors that Affect the Capacitance of a Capacitor
4. Determine the Capacitance of a Capacitor
5. Determine Uses of Capacitors
6. Solve Problems Involving the Arrangement of a Capacitor

## Lesson Note

Capacitors are passive electronic components that are capable of storing electrical energy in an electric field. They are fundamental elements widely used in electronic circuits for various applications, from energy storage to signal processing.

## Lesson Evaluation

Congratulations on completing the lesson on Capacitors. Now that youve explored the key concepts and ideas, its time to put your knowledge to the test. This section offers a variety of practice questions designed to reinforce your understanding and help you gauge your grasp of the material.

You will encounter a mix of question types, including multiple-choice questions, short answer questions, and essay questions. Each question is thoughtfully crafted to assess different aspects of your knowledge and critical thinking skills.

Use this evaluation section as an opportunity to reinforce your understanding of the topic and to identify any areas where you may need additional study. Don't be discouraged by any challenges you encounter; instead, view them as opportunities for growth and improvement.

1. What is the formula for the capacitance of a capacitor? A. C = Q/V B. C = Q * V C. C = V/Q D. C = EA/d Answer: D. C = EA/d
2. What are the types and functions of capacitors? A. Store charge for a short period B. Block DC and allow AC signals to pass C. Used in tuning circuits D. All of the above Answer: D. All of the above
3. What is the relationship between capacitance, area of plates, separation of plates, and medium between the plates? A. C ∝ A B. C ∝ 1/d C. C ∝ 1/∈ D. C = EA/d Answer: D. C = EA/d
4. How are capacitors connected in series? A. Voltage across each capacitor is the same B. Charges on the capacitors are different C. Reciprocal of total capacitance is equal to sum of reciprocals of individual capacitances D. None of the above Answer: C. Reciprocal of total capacitance is equal to sum of reciprocals of individual capacitances
5. What is the energy stored in a capacitor? A. W = 1/2 CV^2 B. W = 1/2 QV C. W = Q^2/C D. W = CV Answer: A. W = 1/2 CV^2

## Past Questions

Wondering what past questions for this topic looks like? Here are a number of questions about Capacitors from previous years

Question 1

A series RLC circuit is said to resonate, when

Question 1

A parallel plate capacitor separated by an air gap is made of 0.8m2 tin plates and 20 mm apart. It is connected to 120 V battery. What is the charge on each plate?

Take εo = 8.85 * 10-12 Fm1

Practice a number of Capacitors past questions