Lesson Notes By Weeks and Term v4 - SHS 3
WAVE
Download the Lessonotes Mobile Ghana app for faster lesson access on Android and iPhone.
WAVE
Download the Lessonotes Mobile Ghana app for faster lesson access on Android and iPhone.
Subject: Physics
Class: SHS 3
Term: 1st Term
Week: 19
Grade code: 3.2.2.LI.1
Strand code: 2
Sub-strand code: 2
Content standard code: 3.2.2.CS.2
Indicator code: 3.2.2.LI.1
Theme: ENERGY
Subtheme: WAVE
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.
This lesson introduces a special and powerful type of light: the laser. We see lasers all around us in Ghana – from the barcode scanners at Shoprite and Melcom that help us check out quickly, to the laser levels used by engineers building our roads and houses, and even in hospitals like Korle-Bu for precise surgeries. Understanding what makes laser light different from the light from a simple torch or a bulb is fundamental to appreciating its many applications in science, technology, and medicine. Today, we will explore the four unique properties that make laser light so special.
A. What is a LASER?
The word LASER is an acronym. It stands for: Light Amplification by Stimulated Emission of Radiation
Let's break this down simply: Light: It is a form of electromagnetic radiation (light). Amplification: This means the light is made much stronger or more intense. Stimulated Emission: This is the special physical process that creates laser light. In an ordinary bulb, atoms release light randomly (spontaneous emission). In a laser, one photon of light hits an excited atom and "stimulates" it to release an *identical* photon, which is a perfect clone of the first one – same colour, same direction, and perfectly in step. This process repeats, creating a cascade of identical photons, thus amplifying the light.
Think of it this way: An ordinary light bulb is like a noisy marketplace where everyone is shouting different things at different times. A laser is like a perfectly trained choir where everyone sings the exact same note, at the exact same time, and in the same direction. B. The Four Main Properties of Laser Light