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: 2
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.
Welcome, students! Today, we are going to explore some very important components in electronics called variable resistors. Think about the fan in your classroom or at home. How do you change its speed from low to high? Or the volume knob on a radio – how does it make the music from Peace FM or Adom FM louder or softer? The magic behind these controls is often a variable resistor. Understanding how they work is fundamental to controlling electricity in circuits, from simple school laboratory experiments to complex industrial machines. This lesson will demystify these components, showing you the physics behind everyday controls.
A. What is a Variable Resistor?
First, let's remember what a standard resistor does. A fixed resistor has a single, constant value of resistance (e.g., 100 Ω). Its job is to limit current or provide a specific voltage drop, but this value doesn't change.
A variable resistor, as the name suggests, is an electronic component whose resistance value can be changed or adjusted. It is also sometimes called an adjustable resistor. Instead of having one fixed value, it provides a range of resistance values, typically from zero up to a maximum value.
The standard symbol for a variable resistor in a circuit diagram is a resistor symbol with an arrow passing through it: