Lesson Notes By Weeks and Term v4 - SHS 3
DIRECT CURRENT
Download the Lessonotes Mobile Ghana app for faster lesson access on Android and iPhone.
DIRECT CURRENT
Download the Lessonotes Mobile Ghana app for faster lesson access on Android and iPhone.
Subject: Physics
Class: SHS 3
Term: 2nd Term
Week: 3
Grade code: 3.3.1.LI.2
Strand code: 3
Sub-strand code: 1
Content standard code: 3.3.1.CS.2
Indicator code: 3.3.1.LI.2
Theme: ELECTRIC FIELD, MAGNETIC FIELD AND ELECTRONICS
Subtheme: DIRECT CURRENT
This page supports the lesson note with a companion video and a short classroom-ready summary.
For class groups and homework, share this lesson page so learners also get the summary, objectives, and full lesson context.
My dear students, electricity is the lifeblood of our modern world. Here in Ghana, from charging our phones to watch the Black Stars, to powering the lights at Kejetia market, to running the machines in our hospitals, we depend on it every second. But how does this electricity behave inside the wires? Why do some devices get hot? Why does a phone charger work for a phone but not for an electric kettle? The answers to these questions begin with a fundamental principle discovered by Georg Ohm. This lesson introduces Ohm's Law, a simple but powerful rule that governs the relationship between voltage, current, and resistance in many electrical circuits.
This topic builds on our prior knowledge of basic electrical terms. Let's do a quick review before introducing the main law. Electric Current (I): The rate of flow of electric charge through a conductor. It's like the amount of water flowing through a pipe per second. The S.I. unit is the Ampere (A). Potential Difference (V): Also known as voltage, it is the work done in moving a unit of positive charge from one point to another in a circuit. It's the "push" or "pressure" that makes the current flow. The S.I. unit is the Volt (V). Resistance (R): The opposition to the flow of electric current. It's like a narrow section or blockage in a water pipe that restricts the flow of water. The S.I. unit is the Ohm (Ω). A. Ohm's Law
In the early 1800s, the German physicist Georg Simon Ohm discovered a fundamental relationship between these three quantities.
Ohm's Law states that:
> *The current flowing through a metallic conductor is directly proportional to the potential difference across its ends, provided that the temperature and other physical conditions remain constant.*