Green Bridge Learning Resource For Electrostatics

Overview

Welcome to the world of electrostatics, a fascinating branch of physics that delves into the study of stationary electric charges and their interactions. In this course material, we will embark on a journey to unravel the mysteries behind the existence of positive and negative charges in matter, the different methods of charging a body, the intricacies of Coulomb's inverse square law, and much more.

At the core of electrostatics lies the concept of charges, where we will learn to identify the fundamental properties of positive and negative charges. Understanding how objects become charged through friction, contact, and induction will be essential as we explore the behavior of charged bodies in different scenarios.

One of the key tools in electrostatics is the electroscope, which allows us to detect the presence of electric charges and understand their nature. We will examine the construction and working principles of the electroscope, learning how it can be used to determine the presence and magnitude of charges.

Coulomb's inverse square law governs the interaction between charges, dictating the force between them based on their magnitudes and separation distances. By applying this law, we will delve into solving problems related to electrostatics and analyzing the behavior of charged particles in various configurations.

As we progress through the course material, we will deduce expressions for electric field intensity and potential difference, crucial concepts that help us understand the influence of charges on their surroundings. Exploring the electric field flux patterns generated by isolated and interacting charges will provide insights into the spatial distribution of electric forces.

Moreover, we will analyze how charges distribute themselves on conductors and investigate the role of lightning conductors in protecting structures from electrical discharges. By studying the principles of electrostatics, we will uncover the mechanisms behind phenomena such as electric discharge and lightning, enriching our understanding of the natural forces at play.

Objectives

Identify Electric Field Flux Patterns of Isolated and Interacting Charges
Apply Coulomb’s Square Law of Electrostatics to Solve Problems
Identify Charges
Analyse the Distribution of Charges on a Conductor and How it is Used in Lightning Conductors
Deduce Expressions for Electric Field Intensity and Potential Difference
Examine Uses of an Electroscope

Lesson Note

Electrostatics is the branch of physics that deals with the study of electric charges at rest. It encompasses various concepts such as electric fields, potentials, charge distributions, and their interactions. Understanding electrostatics is fundamental, as it provides insights into various phenomena like lightning and the functioning of electronic devices.

Lesson Evaluation

Congratulations on completing the lesson on Electrostatics. 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.

What is the fundamental property that gives rise to electric charge? A. Mass B. Volume C. Density D. Protons and Electrons Answer: D. Protons and Electrons
How can a body be charged by induction? A. By rubbing against another body B. By direct contact with a charged body C. By bringing a charged object close without contact D. By immersing in an electric field Answer: C. By bringing a charged object close without contact
What instrument is used to detect the presence of electric charge? A. Ammeter B. Voltmeter C. Electroscope D. Barometer Answer: C. Electroscope
What law describes the force between two charged objects? A. Newton's First Law B. Ohm's Law C. Coulomb's Law D. Hooke's Law Answer: C. Coulomb's Law
What is the SI unit of electric charge? A. Ampere B. Joule C. Ohm D. Coulomb Answer: D. Coulomb
What is the direction of the electric field intensity at a point due to a positive charge? A. Away from the charge B. Towards the charge C. Parallel to the charge D. Perpendicular to the charge Answer: A. Away from the charge
How does lightning occur during a storm? A. Due to magnetic field interactions B. Due to gravitational force C. Due to the flow of electric charges between clouds and the ground D. Due to radioactive decay Answer: C. Due to the flow of electric charges between clouds and the ground
What is the relationship between electric potential and electric field intensity? A. Directly proportional B. Inversely proportional C. No relationship D. Exponential relationship Answer: B. Inversely proportional
What is the purpose of lightning conductors on buildings? A. To attract lightning B. To repel lightning C. To conduct lightning safely to the ground D. To store lightning energy Answer: C. To conduct lightning safely to the ground

Recommended Books

	Physics for Scientists and Engineers Subtitle Electricity and Magnetism Publisher Pearson Year 2016 ISBN 9780321199917
	University Physics with Modern Physics Subtitle Electricity and Magnetism Publisher Pearson Year 2020 ISBN 9780135205973

Past Questions

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

JAMB UTME - Physics - 2023 (Click to take full assessment)

Question 1 Report

Which of the following is NOT an example of elementary modern physics?

Classical mechanics

Quantum mechanics

Special relativity

Nuclear physics

View Answer

WAEC SSCE - Physics - 2022 (Click to take full assessment)

Question 1 Report

(a)(i) State Coulomb's law of electrostatics.

(ii) The electron and proton of a hydrogen atom are separated by a mean distance of 5.2 x 10 $^{- 11}$ m.

Calculate the magnitude of the electrostatic force between the particles.

[e = 1.6 x 10 $^{- 19}$ C, (4 $π$ $E_{0}$ ) $^{- 1}$ = 9.0 x 10 $^{9}$ mF $^{1}$ ]

(b) The diagram below shows a potential divider circuit.

Open photo

i. Show that V $_{o u t}$ = V $_{i n}$ ( $\frac{R_{1}}{R_{1} + R_{2}})$

ii. If $\frac{V_{i n}}{V_{o u t}}$ = 2.5 and R $_{2}$ = 30 $Ω$ , calculate R $_{1}$

iii. Define the volt.

(d) State one application for the cathode ray tube.

Answer

Answer Details

(a)(i) Coulomb's law of electrostatics states that the force of attraction or repulsion between two charged objects is directly proportional to the product of their charges and inversely proportional to the square of the distance between them.

Mathematically, F = kQ1Q2/r^2, where F is the electrostatic force, Q1 and Q2 are the charges on the objects, r is the distance between them, and k is Coulomb's constant.

(ii) Using Coulomb's law, the magnitude of the electrostatic force between the electron and proton of a hydrogen atom can be calculated as follows:

F = k(Q1Q2/r^2) = (9.0 x 10^9 Nm^2/C^2)(1.6 x 10^-19 C)(1.6 x 10^-19 C)/(5.2 x 10^-11 m)^2 = 8.2 x 10^-8 N.

(b)(I) Proof of V $_{o u t}$

Let the current through the circuit be I

V $_{i n}$

= I(R

_{1}

+ R

_{2}

)

I = $\frac{V_{i n}}{R_{1} + R_{2}}$

_{o u t}

= IR

_{2}

II. Calculation of R $_{1}$

;

V $_{o u t}$

= V

_{i n}

(

\frac{R_{1}}{R_{1} + R_{2}}

)

$\frac{V_{o u t}}{V_{i n}} = \frac{R_{1}}{R_{1} + R_{2}}$

\frac{1}{2.5} = \frac{R_{1}}{R_{1} + R_{30}}

_{1}

= 20

Ω

(ii) The Volt The unit of potential difference between two points when one joule of work is done in taking one coulomb of charge between the points

(c) Wood is not suitable for use as the core of transformers because it is not a good conductor of electricity. Transformers require a material with a high magnetic permeability, which allows for efficient transfer of energy between coils. Wood does not have the necessary magnetic properties and can also be damaged by the heat generated during operation.

(d) One application for the cathode ray tube (CRT) is in television and computer displays. A CRT works by producing a beam of electrons that is directed towards a phosphorescent screen, causing it to emit light and create an image. By controlling the path of the electron beam, the image can be manipulated and displayed on the screen. Although CRT technology has largely been replaced by LCD and LED displays, it is still used in some specialized applications such as medical imaging and oscilloscopes.

View Answer