UNIT OVERVIEW

This unit explores how light bends when it passes from one material to another. This bending is called refraction. You will learn Snell's Law, which describes refraction mathematically, and discover total internal reflection — when light gets completely trapped inside a material.

By the end of this unit, you will be able to:

• Apply Snell's Law to calculate angles of refraction and refractive indices
• Explain why light bends when passing between different media
• Calculate critical angles for various material boundaries
• Identify and explain the conditions required for total internal reflection
• Describe real-world applications of total internal reflection
• Conduct an experiment to determine the critical angle of a glass block
• Solve problems involving refraction and total internal reflection

Real-life applications:

1. Fibre optic cables — Undersea cables use total internal reflection to carry internet data across thousands of kilometres
2. Medical endoscopes — Doctors use thin optical fibres to look inside patients' bodies without major surgery
3. Binoculars and periscopes — Prisms rely on total internal reflection
4. Diamond cutting — Gems are cut at precise angles to maximize sparkle through total internal reflection
5. Road mirages — The shimmering "water" on hot roads is caused by total internal reflection in layers of hot air

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