Topic: Light
3.2.1 Reflection of Light
Lesson 1: Laws of Reflection
| Section | Details |
|---|---|
| Objective | – Define and use the terms normal, angle of incidence, and angle of reflection.– Understand that the angle of incidence equals the angle of reflection. |
| Activities | Starter (5 mins): Show a simple reflection using a plane mirror and ask students to describe what they observe.Main (25 mins): 1. Define key terms: normal, angle of incidence, and angle of reflection.2. Demonstrate how to measure these angles using a ray box and a protractor.3. Explain the law of reflection and validate it with a practical experiment.Plenary (10 mins): Students summarize the law of reflection with diagrams. |
| Resources | Plane mirror, ray box, protractor, whiteboard for diagrams. |
| Time | 40 minutes |
| Homework | Draw a ray diagram showing the reflection of light from a plane mirror and label the normal, angle of incidence, and angle of reflection. |
| Assessment | Students explain and demonstrate the law of reflection during the experiment. |
| Past Paper Practice | IGCSE Physics 0625/21/M/J/20 Q2(b). |
Lesson 2: Optical Images in Plane Mirrors
| Section | Details |
|---|---|
| Objective | – Describe the formation and characteristics of an optical image by a plane mirror. |
| Activities | Starter (5 mins): Ask students if they see themselves “exactly the same” in a mirror and why.Main (25 mins): 1. Demonstrate the formation of an image using a plane mirror.2. Explain the characteristics of the image (same size, same distance, virtual, laterally inverted).3. Use ray diagrams to illustrate how the image is formed.Plenary (10 mins): Students describe the characteristics of images formed by plane mirrors. |
| Resources | Plane mirror, object (e.g., candle or pencil), ray diagram worksheet. |
| Time | 40 minutes |
| Homework | Draw and label a ray diagram to show how an image is formed in a plane mirror. |
| Assessment | Students explain the image formation and its characteristics during the plenary and through their ray diagrams. |
| Past Paper Practice | IGCSE Physics 0625/22/M/J/19 Q3(b). |
3.2.2 Refraction of Light
Lesson 3: Introduction to Refraction
| Section | Details |
|---|---|
| Objective | – Define and use the terms normal, angle of incidence, and angle of refraction.– Understand the concept of refraction as the bending of light due to speed changes. |
| Activities | Starter (5 mins): Show a pencil in a glass of water and ask why it appears bent.Main (25 mins): 1. Define key terms: normal, angle of incidence, and angle of refraction.2. Demonstrate refraction using a glass block and ray box.3. Use diagrams to show light bending at the boundary between two media.Plenary (10 mins): Students explain why light bends when entering a denser medium. |
| Resources | Glass block, ray box, protractor, whiteboard for diagrams. |
| Time | 40 minutes |
| Homework | Draw a ray diagram showing refraction through a rectangular glass block. |
| Assessment | Students identify and explain the angles of incidence and refraction during the experiment. |
| Past Paper Practice | IGCSE Physics 0625/31/O/N/20 Q3(a). |
Lesson 4: Critical Angle and Total Internal Reflection
| Section | Details |
|---|---|
| Objective | – Define the critical angle and describe internal and total internal reflection.– Understand applications of total internal reflection, such as optical fibers. |
| Activities | Starter (5 mins): Show a demonstration of a laser beam reflecting inside a plastic tube and ask students why it stays inside.Main (25 mins): 1. Define the critical angle and total internal reflection.2. Demonstrate total internal reflection using a semi-circular glass block.3. Explain applications of total internal reflection (e.g., optical fibers).Plenary (10 mins): Students summarize the conditions required for total internal reflection. |
| Resources | Semi-circular glass block, ray box, laser pointer, diagrams of optical fibers. |
| Time | 40 minutes |
| Homework | Research one application of optical fibers and write a short paragraph explaining it. |
| Assessment | Students explain the concept of total internal reflection during the plenary and describe its applications. |
| Past Paper Practice | IGCSE Physics 0625/42/M/J/19 Q4(c). |
3.2.3 Thin Lenses
Lesson 5: Action of Thin Lenses
| Section | Details |
|---|---|
| Objective | – Describe the action of thin converging and diverging lenses on a parallel beam of light.– Define focal length, principal axis, and principal focus. |
| Activities | Starter (5 mins): Show a magnifying glass and ask how it makes objects appear larger.Main (25 mins): 1. Explain the difference between converging and diverging lenses.2. Use diagrams to show how each lens affects parallel light rays.3. Define focal length and principal focus.Plenary (10 mins): Students draw and label diagrams of converging and diverging lenses. |
| Resources | Convex and concave lenses, ray box, lens diagrams. |
| Time | 40 minutes |
| Homework | Draw ray diagrams showing the action of converging and diverging lenses on parallel light rays. |
| Assessment | Students explain the action of each lens and complete diagrams during the plenary. |
| Past Paper Practice | IGCSE Physics 0625/32/O/N/20 Q3(b). |
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