Physics Keypoints: Electrostatics; This study material is suitable for students sitting for the following exams: JAMB, WAEC, NECO, GCE, IJMB, and JUPEB. Electrostatics is a branch of physics that focuses on the study of stationary electric charges and the interactions between them.
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It explores fundamental concepts such as positive and negative charges, methods of charging bodies, the behavior of electric fields, and the intriguing phenomenon of lightning. In this article, we’ll delve into each of these topics in depth.
(i) Existence of Positive and Negative Charges in Matter
Matter is composed of atoms, and atoms contain subatomic particles, including protons, neutrons, and electrons. Among these, protons are positively charged, electrons are negatively charged, and neutrons are neutral. This duality gives rise to the existence of positive and negative charges in matter.
Atoms are electrically neutral, with the number of protons equaling the number of electrons. However, the movement of electrons between atoms creates charged objects. For example, when an object loses electrons, it becomes positively charged, and when it gains electrons, it becomes negatively charged.
(ii) Charging a Body by Friction, Contact, and Induction
Objects can acquire electric charges through various methods:
- Friction: When two dissimilar materials are rubbed together, electrons can be transferred from one material to the other, resulting in one object becoming positively charged and the other negatively charged.
- Contact: Charging by contact occurs when a charged object is brought into contact with an uncharged object. Electrons are transferred from the charged object to the uncharged one, equalizing the charges.
- Induction: Induction involves the rearrangement of electrons within a conductor when it is exposed to a nearby charged object, without direct contact. This results in temporary redistribution of charges in the conductor.
(iii) Electroscope
An electroscope is a device used to detect the presence of electric charges. It consists of a vertical metal rod with two thin, lightweight metal leaves at the bottom. When a charged object is brought close to the metal rod, the leaves either repel each other due to the like charges or collapse together due to opposite charges. The electroscope provides a qualitative indication of the presence and type of electric charge.
(iv) Coulomb’s Inverse Square Law, Electric Field, and Potential
(v) Electric Field Intensity and Potential Difference
(vi) Electric Discharge and Lightning
Electric discharge refers to the sudden flow of electric current between two charged objects with differing potentials. Lightning is a dramatic example of electric discharge in nature. It occurs when charged regions in clouds or between the clouds and the ground discharge as a result of the accumulation of electric charges.
This discharge produces visible lightning bolts and thunder. Lightning conductors or lightning rods are used to protect buildings and structures from lightning strikes by providing a safe path for the electrical discharge to reach the ground, thereby preventing damage or fires.
In summary, electrostatics unveils the mysteries of electric charges and their behavior, from the basic concept of positive and negative charges to the application of Coulomb’s law, electric fields, and potential. Understanding these principles is crucial for various applications, from electrical engineering to the safe protection of structures from lightning.
