Refraction of Light
Relate changes in wave speed to refractive index, bending, critical angle and total internal reflection.
How to study Higher Physics
Move between physical models, relationships, units, graphs and justified conclusions, while using current official materials for exact paper and assignment conditions.
Core concepts
Concept 1
absolute refractive index
Exam cue: Angles are measured from the normal.
Concept 2
Snell’s law
Exam cue: Frequency stays constant at a stationary boundary.
Concept 3
frequency and wavelength across a boundary
Exam cue: Total internal reflection requires travel from higher to lower refractive index.
Concept 4
frequency dependence of refractive index
Concept 5
critical angle and total internal reflection
Risk pitfalls and guardrails
Measuring angles from the surface.
Guardrail: Check assumptions, prefixes, units, significant figures and whether the statement is supported by evidence.
Changing frequency on refraction.
Guardrail: Check assumptions, prefixes, units, significant figures and whether the statement is supported by evidence.
Applying the critical-angle condition in the wrong direction.
Guardrail: Choose a positive direction and preserve signs through the calculation before interpreting the result.
Memory anchors
Absolute refractive index
n = c/v.
Snell’s law
n₁ sin θ₁ = n₂ sin θ₂.
Into a slower medium
The ray bends toward the normal.
Boundary frequency
Frequency remains unchanged.
Critical angle
The refracted angle is 90° when light travels toward the lower-index medium.
Total internal reflection
Incidence is in the higher-index medium and exceeds the critical angle.
Checkpoint rule
Do the check-up only after you can summarize each concept in one sentence and identify one dangerous pitfall from memory.
Knowledge Check (after reading)
Short check-up to confirm understanding of this module.
Check-up Questions
What is the absolute refractive index n of a medium?
Light travels at 2.0×10⁸ m s⁻¹ in glass. Use c=3.0×10⁸ m s⁻¹. Find the glass's absolute refractive index.
Answer all questions to submit.
Next step personalized recommendations
Continue learning
Move forward only after this module is stable.
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