Study Notes
Refraction, reflection, and polarisation are key concepts in wave physics, involving the bending, bouncing, and orientation of waves, respectively.
- Refractive Index — a measure of how much light bends when entering a medium. Example: Light slows down and bends when moving from air into water.
- Snell’s Law — relates the angles of incidence and refraction to the refractive indices of two media. Example: n1 * sin(θ1) = n2 * sin(θ2).
- Critical Angle — the angle of incidence above which total internal reflection occurs. Example: Light traveling from water to air reflects entirely back into the water at angles greater than the critical angle.
- Total Internal Reflection — occurs when light reflects completely within a medium rather than refracting out. Example: Optical fibers use total internal reflection to transmit light.
- Plane Polarisation — the restriction of wave oscillations to a single plane. Example: Sunglasses use polarising filters to reduce glare by blocking certain light waves.
Exam Tips
Key Definitions to Remember
- Refractive Index
- Snell’s Law
- Critical Angle
- Total Internal Reflection
- Plane Polarisation
Common Confusions
- Mixing up refraction and reflection
- Misunderstanding the concept of critical angle
- Confusing polarisation with other wave properties
Typical Exam Questions
- What is Snell’s Law? Answer: It relates the angles of incidence and refraction to the refractive indices of two media.
- How is the critical angle calculated? Answer: Using the formula sin(C) = 1/n.
- What happens during total internal reflection? Answer: Light reflects completely within a medium.
What Examiners Usually Test
- Understanding of Snell’s Law and its application
- Ability to calculate the critical angle
- Explanation of how polarisation affects wave propagation