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Refraction of light at plane surfaces

Kerala Board · Class 9 · Science

Quick revision notes for Refraction of light at plane surfaces — Kerala Board Class 9 Science. Key concepts, formulas, and definitions for last-minute revision.

45 questions20 flashcards5 concepts

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Key Topics to Revise

1

What is Refraction?

  • Refraction is the bending of light when it passes from one transparent medium to another
  • Light changes direction due to change in speed at the interface of two media
  • The bending occurs because light follows Fermat's principle - it takes the path requiring least time
2

Refractive Index

  • Refractive index is a measure of how much light slows down in a medium compared to vacuum
  • Absolute refractive index: n = c/v, where c is speed of light in vacuum, v is speed in medium
  • Relative refractive index compares speeds of light in two different media
3

Snell's Law

  • Snell's law relates angle of incidence and angle of refraction quantitatively
  • The ratio sin i/sin r is constant for given pair of media
  • Can be derived using Fermat's principle of least time
4

Total Internal Reflection

  • Occurs only when light travels from denser to rarer medium
  • Critical angle is the angle of incidence when angle of refraction becomes 90°
  • For angles greater than critical angle, no refraction occurs - complete reflection

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Full Notes

Key Concepts

The process of changing speed atThe ratio of speed of lightThe fundamental law governing refractionCritical angle C is the angleWhen light passes through a parallel

Frequently Asked Questions

What are the important topics in Refraction of light at plane surfaces for Kerala Board Class 9 Science?
Refraction of light at plane surfaces covers several key topics that are frequently asked in Kerala Board Class 9 board exams. Focus on the core concepts listed on this page and practise related questions to build confidence.
How to score full marks in Refraction of light at plane surfaces — Kerala Board Class 9 Science?
Start by understanding all key concepts. Practise previous year questions from this chapter. Revise formulas and definitions regularly. Use flashcards for quick revision before the exam.

Sources & Official References

Content is aligned to the official syllabus. Refer to the board website for the latest curriculum.

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