OCR A-Level Physics A H556
Practical Skills in the Written Papers
The Practical Endorsement
Physical Quantities and Units
Making Measurements and Analysing Data
Nature of Quantities
Motion
Forces in Action
Work, Energy and Power
Materials
Newton’s Laws of Motion and Momentum
Charge and Current
Energy, Power and Resistance
Electrical Circuits
Waves
Quantum Physics
Thermal Physics
Oscillations
Gravitational Fields
Astrophysics and Cosmology
Capacitors
Electric Fields
Electromagnetism
Nuclear and Particle Physics
Waves
Critical angle and total internal reflection
- 1 thing to know
- Papers 2 and 3
Overview
Recall questions on the critical angle, its relationship to refractive index, total internal reflection and the conditions for it, and investigating it with a semi-circular block.
What you need to know
Answer each one before you reveal it.
Questions from this subtopic
Each one with the model answer underneath.
- 1
What is varied during an investigation of total internal reflection using a semi-circular block?
Model answer
The angle of incidence at the flat face.
- 2
What phenomena can be observed at the flat face of a semi-circular block as the angle of incidence is increased?
Model answer
Refraction and total internal reflection.
- 3
Define the critical angle.
Model answer
The angle of incidence in the denser medium at which the angle of refraction in the less dense medium is exactly 90°.
- 4
State the equation relating the critical angle to the refractive index.
Model answer
sin C = 1/n, where C is the critical angle and n is the refractive index of the denser medium relative to the less dense medium.
- 5
Write the formula used to calculate the critical angle from the refractive index.
Model answer
C = arcsin(1/n).
- 6
Define total internal reflection.
Model answer
Total internal reflection occurs when light travelling in a denser medium strikes the boundary with a less dense medium at an angle greater than the critical angle.
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