Critical angle
What Critical angle means in Physics A-Level, as defined for AQA, OCR.
Definitions of Critical angle
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Reference: AQA
Related to the refractive indices by sin C = n₂ / n₁, where n₁ is the core index and n₂ is the cladding index, and n₁ must exceed n₂ for guidance to be possible.
The angle of incidence in the denser medium for which the angle of refraction is 90°, so the refracted ray emerges along the boundary.
The angle of incidence at the flat face at which the refracted ray eventually grazes the boundary.
Topics that use Critical angle
- Refraction at a plane surface (AQA A-Level)
- Electromagnetic waves (OCR A-Level)
Related terms
- Total internal reflection
- Absorption
- Acceptance angle
- Material dispersion
- Modal dispersion
- Orders of magnitude across the spectrum
- Pulse broadening
- Refraction
Using Critical angle in the exam
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